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Automatic Gas Dryers


Gas and electric dryers are similar in operation, with the exception of how the air is
heated for drying the clothes. The electric components in a gas dryer will operate
on 120 volts only. They use liquefied petroleum gas (LP or LPG) or natural gas as
a fuel, air (oxygen), and an ignition source to produce a flame. The gas burner can produce
between 18,000 and 30,000 BTU/hr of heat, whereas the electric dryer produces between
17,000 and 19,000 BTU/hr of heat. All of the mechanics of the electric dryer, with the
exception of the electric heater, are incorporated into the gas dryer.
The dryer will circulate the air, apply heat, and tumble the clothes to increase the surface
exposure to remove water from the clothes by evaporation, and then vent the combustion
by-products to the outside of the residence. The gas burner assembly includes a gas shutoff
valve, burner, automatic solenoid gas control valve, pressure regulator, an ignition system,
temperature controls, and safety limit controls.
The operating controls will prevent the burner from coming on if certain conditions are
not met. Before the dryer can start, the door must be closed (closing the door switch), and
then the consumer will set the timer and press the start button, starting the cycle. If for any
reason the motor does not start, the burner operation will not commence. On some models,
a belt switch is incorporated into the circuitry to prevent the burner from operating if the
dryer belt breaks.
The safety switches will prevent burner operation if the temperature exceeds their
pre-set limit. These safety switches are located on the burner chamber, bulkhead, and
exhaust passages.
Top-of-the-line models offer electronic controls, moisture sensors to sense how much
water is remaining in the clothes, and automatic cycles designed for custom drying a variety
of fabrics and load sizes.
This chapter will provide the basic skills needed to diagnose and repair automatic gas
dryers. Figure 21-1 identifies where the components are located within the automatic gas
dryer. However, this illustration is used as an example only. The actual construction and
features might vary, depending on what brand and model you are servicing.
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Safety First
Any person who cannot use basic tools or follow written instructions should not attempt to
install, maintain, or repair any automatic dryers. Any improper installation, preventive
maintenance, or repairs could create a risk of personal injury or property damage.
If you do not fully understand the installation, preventive maintenance, or repair
procedures in this chapter, or if you doubt your ability to complete the task on the automatic
dryer, please call your service manager.
Do not store any flammable materials near a gas dryer, and avoid ignition sources in the event
you smell gas leaking. Make sure you have proper ventilation when servicing the gas dryer to prevent
carbon monoxide (CO) poisoning.
The following additional precautions should also be followed:
. Never bypass (or interfere with) the operation of any switch, component, or feature.
. Be careful of sharp edges when working on the dryer.
. The dryer produces combustible lint, and the area should be kept clean.
. Never remove any ground wires from the dryer or the third (grounding) prong
from the service cord.
Gas burner assembly
Side-open
door
Belt
Electronic
controls
Drum
and
drying
rack
Lint filter
FIGURE 21-1 The location of components in a typical automatic gas dryer. The consumer has a choice
between a drop-down or side-open door.
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. Never use an extension cord to operate a dryer.
. The wiring used in dryers is made with a special heat-resistant insulation. Never
substitute it with ordinary wire.
. Always follow the use and care guide instructions from the dryer manufacturer.
. Always keep combustible products away from the gas dryer.
. Keep the dryer clean of soot, grease, and food spillages.
. Teach your children not to play near or with the dryer.
. Always have a fire extinguisher nearby just in case of mishaps that might lead
to a fire.
. Have a smoke detector and a carbon monoxide detector installed in the home, and
check the batteries yearly.
. Make sure the gas dryer is properly vented according to the manufacturerfs
recommendations. Never exhaust the dryer into a chimney, a common duct, an attic,
or a crawl space.
Before continuing, take a moment to refresh your memory of the safety procedures
in Chapter 2.
Automatic Gas Dryers in General
Much of the troubleshooting information in this chapter covers automatic gas dryers in general,
rather than specific models, in order to present a broad overview of service techniques. The
illustrations that are used in this chapter are for demonstration purposes only to clarify
the description of how to service dryers. They in no way reflect upon a particular brandfs
reliability.
Gas Supply Requirements
The gas dryer is manufactured and shipped for natural gas installation. If the gas supply to
the home is liquefied petroleum gas (LP or LPG), the dryer will then have to be converted.
When installing the gas supply line to the dryer, the shutoff valve must be within six feet of
the product. This will make it easier to locate and shut off the supply of gas to the product for
servicing. The recommended gas supply line size should be 1/2-inch IPS pipe; it is acceptable to
use 3/8-inch tubing for less than 20 feet to connect to the shutoff valve, only if it is approved by
the local codes in your area. The gas supply line must include a 1/8-inch NPT-plugged connection
between the dryer and shutoff valve for testing the gas pressure (Figure 21-2).
For more information regarding gas appliance installations and gas supply line installations,
refer to the following sources:
. National Fuel Gas Code
. International Fuel Gas Code
. The local gas codes in your area
. The manufacturerfs recommendations
. The AGA (American Gas Association)
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Gas Tests for Gas Dryers
The following testing procedures should be carried out on every service call after repairing
the gas dryer:
. To test the manifold pressure on the dryer, connect a manometer to the pressure tap
on the gas valve. During the burner operation, the manometer reading should be
between 2.5 and 4.0 inches water column.
. Inspect the flames entering the drying chamber, block off the exhaust vent, and
inspect the flame length. The flames should not be entering the drying chamber.
. Inspect for flashback into the burner, block off the exhaust vent, and inspect for
flashback into the burner during ignition.
. Checking for power interruption, interrupt the power momentarily for two seconds.
The motor should not continue to run when the power is restored. The gas valve
should not open when the power is restored until the ignitor is re-energized.
. Check for carbon deposit, and inspect the heater housing and burner assembly for
carbon deposits.
. Inspect the ignition time of the ignitor (glow-bar); the time required for the glow-bar
to light the gas burner should be between 50 and 90 seconds depending on the
model serviced. Check with the technical data sheet.
. Check the ignition power; this is the power required for the glow-bar to light the
gas (300 to 850 watts depending on which glow-bar ignitor is used in the dryer).
. Check the static pressure of the air flow in the dryer. With the dryer exhaust 100
percent blocked, measure the static pressure with a manometer. The minimum
reading should be 1.6-inch water column.
3/8'' pipe to flare adapter fitting
1/8'' NPT plugged test
gauge connection
1.2'' NPT-approved gas
supply line
3/8'' tubing Gas shutoff valve
FIGURE 21-2 A typical gas supply line to the dryer. The plugged test gauge connection will be used for
testing the gas pressure.
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Principles of Operation
The clothes are placed into the dryer according to the manufacturerfs recommendation for
proper loading. Next, the proper cycle is selected, and the dryer start button is pressed. The
combination of the timer, the switches, thermistors, and/or the thermostats regulates the air
temperature within the drum and the duration of the drying cycle. During the drying cycle,
room air is pulled into the dryer drum from the lower rear (or sometimes the front) of the
cabinet, depending on which model the consumer owns (Figures 21-3 and 21-4). The air is
pulled through the gas burner assembly (combustion chamber), the drum, the lint screen,
down through the lint chute, and through the fan housing. It is then pushed out of the exhaust
duct. The drive motor, blower wheel, belt, and pulleys cause the drum to turn in a clockwise
rotation at 40 to 60 RPM, and the air to move through the dryer. The belt wraps around the
drum, motor pulley, and idler pulley. The blower wheel is secured to one end of the drive
motor shaft, or there may be a separate motor to turn the blower wheel. As the drive motor
turns, the drum rotates, moving the clothes. At the same time, the blower wheel turns, moving
the air. The gas burner assembly will cycle on and off, according to the temperature selected.
Functions and Cycles
Gas automatic dryers use three basic functions to operate:
. Heat is supplied by a gas burner.
. Air is drawn into the dryer. It is heated and circulated through the tumbling clothes.
Then the warm, moisture-laden air is drawn through the lint screen and is vented
through the duct system to the outside.
. Tumbling of the clothes is accomplished with a motor that drives a belt, which
rotates the drum.
Lint
ilter
Gas dryer
Drum felt
Trap duct
seal
Exhaust air
Combustion
chamber
Inlet
air
FIGURE 21-3
Typical air low pattern
in an automatic gas
dryer.
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The cycles of a gas automatic dryer are as follows:
. Timed dry cycle The timed dry cycle is controlled by the amount of time selected
on the timer. The temperature in the dryer is controlled by a thermostat or a
thermistor, which turns the gas burner on and off throughout the timed cycle.
. Automatic dry cycle The automatic dry cycle is not controlled by the timer. This
cycle is controlled by the cycling thermostats or thermistors. Heat is supplied to dry
the clothes, and it will continue until the temperature in the drum reaches the selected
cutout setting of the thermostat or thermistor. When the thermostat or thermistor is
satisfied, the gas burner shuts off and the timer motor is activated. However, certain
variables can control the cycle, which will cause the cycling of the thermostat or
thermistor before the end of the cycle. (You may want to check the service manual for the
model you are servicing.)
. Permanent press and knit cycles The permanent press and knit cycles are controlled
by the amount of time selected on the timer. The temperatures of these cycles are
controlled by the temperature rating of the cycling thermostats or by the thermistors
that are located within the cabinet, on the exhaust duct, and in the air supply. On
some models, the user can select the desired type of heat setting with the
temperature selector switch, located on the control panel.
. Air dry The air-dry cycle is controlled by the amount of time selected on the timer.
This cycle uses the air to dry the clothes. The gas burner is not used at all during
this cycle.
Safety thermostat
Safety thermostat
Inlet temperature
sensor
Inlet temperature sensor
Outlet temperature sensor
Outlet backup
t‹
t‹
t‹
Dryer
cabinet
Gas
combustion
chamber
Heater
pan/electric
coils
Drum Lint trap Blower Exhaust
Diffuser
FIGURE 21-4 Gas dryer air low system.
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Electrical Requirements and Tests for Gas Dryers
The dryer must be grounded. In the event of a malfunction, grounding will reduce the risk of
electrical shock by a path of least resistance for electrical current. The dryer is equipped with
a 120-volt power supply cord having an equipment-grounding conductor and a grounding
three-prong plug. The plug must be plugged into a three-prong receptacle (120 volts) that is
properly grounded in accordance with all local codes and ordinances (Figure 21-5). Never
remove the grounding prong from the power cord.
While performing a service call on a gas dryer the following electrical tests should be
performed:
. Continuity Use your multimeter and set it on the ohms scale. When measuring
resistance between the terminal block ground and any exposed unpainted metal
cabinet component, including control shafts and switches, there should be no more
than 0.1 ohms resistance reading.
. Motor power Perform an audit on the motor (power required after 20 seconds
with no load, and the motor is turning in the clockwise direction, and the electric
heater is turned off). The reading should be between 200 and 280 watts. Next,
perform a line test (power required after 1 to 5 seconds with no clothes in the dryer,
the motor is turning in a clockwise direction, and the electric heater is turned off).
The reading should be between 210 and 290 watts. If you do not have a wattmeter,
use the Ohmfs Law formula to convert to watts.
. Low voltage start The minimum voltage needed to start the dryer motor is 100
VAC, 60 Hz (200 volts for 230 VAC, 50 Hz dryers). Place about 25 pounds of clothing
with 100 percent moisture into the dryer and set the dryer at its maximum heat
setting. Turn on the dryer and measure the voltage at the start of the dryer cycle.
The voltage should not be below the listed voltage for any part of the cycle.
. Drum temperatures The following test will be run with the exhaust duct vent
disconnected from the dryer. Take your multimeter temperature thermal couple and
place it in the lint grill about 1 to 2 inches. You will need to set the dryer timer as
Do not cut off the grounding
prong or bypass grounding.
The gas dryer must be grounded.
Grounding type
wall receptacle
120 v gas dryer
Power code with
3-prong grounded plug
FIGURE 21-5
This igure illustrates
the proper way to plug
in a gas dryer power
cord.
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needed for this test. The recordable temperature is to be the maximum temperature
reading after the third cycle when the heater cycles off. There should not be any
clothes in the dryer for this test. Each time the thermostat or thermistor cycles open,
there should be equal to or higher than opening temperature for the next lower
temperature setting.
. Maximum heating temperature when the heater cycles off is 120 to 180 degrees
Fahrenheit.
. Medium heating temperature when the heater cycles off is 105 to 145 degrees
Fahrenheit.
. Low heating temperature when the heater cycles off is 95 to 130 degrees Fahrenheit.
Gas Dryer Maintenance
Automatic dryers must be cleaned periodically. The excess lint must be removed to prevent
the possibility of a fire and the possibility of the dryer not functioning properly. Most
models have a service panel on the front of the dryer for accessibility. On other models, the
front panel will have to be removed. The outside of the cabinet should be wiped with a
damp cloth. It is recommended that the components be inspected for wear and tear; if
repairs are needed, they should be made as soon as possible. The gas burner assembly must
be inspected and cleaned yearly. The dryer gas line must also be inspected and checked for
gas leaks yearly.sooner if you suspect a gas leak.
Vent System
A clogged or restricted vent system can cause the dryer not to function properly. The following
symptoms can occur:
. The clothes take too long to dry.
. The clothes are too hot at the end of the cycle.
. Unusual noises coming from the dryer.
. At the end of the cycle, the clothes are damp and hot.
. The sensors and thermostats fail to operate properly.
. Complications in the burner assembly.
Proper Exhausting of the Dryer
Proper exhausting instructions for the model being installed are available through the
manufacturer. Each manufacturer has its own specifications for the size and the length of
the ductwork needed to run its dryer properly. The maximum length of the exhaust system
depends upon the type of duct, the number of elbows, and the type of exhaust hood used.
Figure 20-8 illustrates a typical dryer exhaust installation.
The following guide is recommended for the exhausting of a dryer:
. Keep the duct length as short as possible.
. Keep the number of elbows to a minimum to minimize the air resistance.
. Never reduce the diameter of round ductwork below 4 inches.
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. Install all exhaust hoods at least 12 inches above ground level.
. The exhaust duct and exhaust hood should be inspected periodically and cleaned, if
necessary.
. All duct joints should be taped. Never use screws to join the duct joints together.
Screws protruding into the duct will cause lint buildup, and this will eventually
clog the duct.
. Never exhaust the dryer into any wall, ceiling, attic, or under a building.
. Accumulated lint could become a fire hazard, and moisture could cause damage.
. If the exhaust duct is adjacent to an air conditioning duct, the exhaust duct must be
insulated to prevent moisture buildup.
Exhaust Ducting
The more that the dryer is used, the more the exhaust ducts and vent hood must be inspected
to prevent duct blockages and lint fires. The exhaust ducting and vent hood must be cleaned
at least once a year for peak performance in drying.
When installing ductwork, separate all turns by at least 4 feet of straight duct, including
the distance between the last turn and the dampened wall hood. If a turn is 45o or less, it can
be ignored in figuring out duct distance. If you have two 45o turns, count it as one 90o turn.
Also, each turn over 45o should be counted as one 90o turn (see Figures 20-9, 20-10, 20-11,
20-12, and 20-13).
When sealing the joints of the exhaust ducts with duct tape, the male end of each section
of duct must point away from the dryer to prevent lint buildup. Also, never use screws to
connect the ducts together; this will cause lint buildup. Any ductwork that runs through an
unheated area or is near air conditioning must be insulated to prevent condensation and lint
buildup (check with your local codes and ordinances).
Safety note: All exhaust ductwork must exhaust to the outside of a building to prevent
lint buildup and fire. Do not terminate exhaust ductwork in a chimney, any gas vent, under
enclosed floor (crawl space), common duct with a kitchen exhaust, or into an attic because
the lint accumulation will cause a fire. Finally, never block incoming or exhausted air
supplies; this will cause the dryer to run inefficiently and may cause a fire.
Step-by-Step Troubleshooting by Symptom Diagnosis
In the course of servicing an appliance, donft overlook the simple things that might be
causing the problem. Step-by-step troubleshooting by symptom diagnosis is based on
diagnosing malfunctions, with possible causes arranged into categories relating to the
operation of the dryer. This section is intended only to serve as a checklist to aid you in
diagnosing a problem. Look at the symptom that best describes the problem that you are
experiencing with the dryer, and then correct the problem.
Gas Odors
. Check the pilot light and gas valve.
. Check for a gas leak in the supply line.
. Check the ventilation system.
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Dryer Will Not Run
. Do you have 120 volts at the dryer?
. Test the door switch for continuity of the switch contacts. In addition, make sure the
dryer door closes properly.
. Test for continuity of the motor windings. Also check for a grounded motor.
. Test the timer for continuity of the switch contacts.
. Test the gpush to starth switch for continuity of the switch contacts.
. Check for broken or loose wiring. Also check the wire terminal connections that
connect to the different components.
. Check the thermal fuse.
. On electronic models, check for unusual display readouts and/or error codes.
No Heat
. Check the controls setting.
. Do you have 120 volts at the dryer?
. Check the gas valve. Is the gas turned on?
. Check the thermal fuse.
. Check the thermostats.
. Check the ignitor. Does it light up?
. Check the flame sensor.
. Check for proper ventilation.
. On electronic models, check for unusual display readouts and/or error codes.
Dryer Will Not Turn Off
. Check the control settings. Does the timer advance?
. Check the electronics. Run the self-diagnostic test mode.
. Check the thermistor. Is it open or shorted?
. Check the thermostats. Check continuity.
. On electronic models, check for unusual display readouts and/or error codes.
Dryer Runs and Heats, but the Clothes Wonft Dry
. Check for a defective thermostat or thermistor. Use a thermometer to check the duct
temperatures during the cycling of the dryer.
. Check for a loose pulley or blower wheel. Inspect and tighten the blower wheel.
. Check for restricted air flow in the dryer.
. Check the vent system. Is the vent hose behind the dryer kinked?
. Check the thermostats and thermistors.
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. Check the lint filter. Does the lint filter need cleaning?
. On electronic models, check for unusual display readouts and/or error codes.
The Burner Will Not Ignite
. Make sure that the gas supply to the dryer is turned on.
. Check the gas line for debris.
. Check the line to the burner for a blockage. If blocked, locate the source and correct.
. Test the value of the thermocouple; replace if necessary.
. Test the thermostat; replace if necessary.
. Check the installation and fresh air supply.
. Check the ignition components.
. On electronic models, check for unusual display readouts and/or error codes.
The Burner Flame Is Too High
. Check the dryer installation. Is the orifice too large? You can change the orifice and
retest the burner.
. Check for sufficient secondary air supply.
. Check the venting system.
. Check the burner air shutter. Is it adjusted correctly?
The Pilot Flame Is Too Small
. Check the pilot line and orifice for debris.
. Check the gas pressure to the dryer.
. Test the gas pressure at the regulator.
A Yellow Burner Flame
. Check for sufficient secondary air supply.
. Check the gas pressure.
. Check the venting system.
. Check the burner line for debris.
. Check the dryer installation.
. Check the burner orifice for obstruction.
The Burner Flame Floats and Lifts Off the Ports
. Check the dryer installation. Is the orifice too large? You can change the orifice and
retest the burner.
. Check for high gas pressure.
. Check the vent system and burner. Locate the source and correct the problem.
. Check for drafts that can blow the flame off the burner.
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The Formation of Soot (Smoke and Carbon)
. Check for sufficient secondary air supply.
. Check the ventilation system.
. Check for a yellow burner flame.
. Check for low gas pressure to the dryer.
. Is the dryer installed in a confined space?
Combustion Odors
. Check for sufficient secondary air.
. Check the ventilation system and the burner.
. Is the dryer installed in a confined space?
For additional symptoms, see Chapter 20.
Repair Procedures
Each repair procedure is a complete inspection and repair process for a single dryer
component, containing the information you need to test a component that might be faulty
and to replace it, if necessary.
Any person who cannot use basic tools should not attempt to install, maintain, or repair
any electric dryer. Any improper installation, preventative maintenance, or repairs will
create a risk of personal injury, as well as property damage. Call the service manager if
installation, preventative maintenance, or the repair procedure is not fully understood.
Electronic Control Board and User Interface Controls
On some models the electronic control board and user interface controls replace the
electromechanical timer and rotary selection switches (see Figures 21-1 and 20-18). The
electronic control board is located behind the control panel.
The typical complaints associated with the electronic control board or the user interface
controls are:
. The dryer wonft run or power up.
. Unable to program the dryer.
. The display board will not display anything.
. One or more key pads will not accept commands.
. Unusual display readouts and/or error codes.
To prevent electrostatic discharge (ESD) from damaging expensive electronic
components, follow the steps in Chapters 6 and 11.
To handle these problems, perform the following steps:
1. Verify the complaint. Verify the complaint by operating the dryer. Turn off the
electricity to the appliance and wait for two minutes before turning it back on. If a
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fault code appears, look up the code. If the dryer will not power up, locate the
technical data sheet behind the control panel or for diagnostics information. On
some models you will need the actual service manual for the model you are
working on to properly diagnose the dryer. The service manual will assist you in
properly placing the dryer in the service test mode for testing the dryer functions.
2. Check for external factors. You must check for external factors not associated with
the appliance. Are there 120 volts of electricity to the dryer? The voltage at the
receptacle is between 108 volts and 132 volts during a load on the circuit. Do you
have the correct polarity? (See Chapter 6.)
3. Disconnect the electricity. Before working on the dryer, disconnect the electricity.
This can be done by pulling the plug out of the wall receptacle. Or disconnect the
electricity at the fuse panel or circuit breaker panel. Turn off the electricity.
WARNING Some diagnostic tests will require you to test the components with the power turned on.
When you disassemble the control panel, you can position it in such a way that the wiring will
not make contact with metal. This act will allow you to test the components without electrical
mishaps.
4. Shut off the gas supply. Before you begin servicing any gas components, shut off
the supply of gas to the appliance. The shutoff valve should be within 6 feet of the
gas appliance.
5. Remove the console panel to gain access. Begin by removing the screws from the
dryer top (for front-loading models only) to gain access to the electronic control
board. Remove the console panel screws to gain access to the user interface controls
(see Figure 20-18). On top-loading models, the console will roll upwards or toward
you after you remove the console screws.
6. Test the electronic control board and user interface controls. If you are able to run
the dryer diagnostic test mode, check the different functions of the dryer. Use the
technical data sheet for the model you are servicing to locate the test points from the
wiring schematic. Check all wiring connections and wiring. Using the technical data
sheet, test the electronic control or user interface controls, input voltages, and output
voltages. On some models, fuses are soldered to the printed circuit board (PCB).
These fuses must be tested first before condemning the component.
7. Remove the electronic control board and user interface control. To remove the
defective component, remove the screws that secure the board to the control panel
or dryer frame. Disconnect the connectors from the electronic control board or user
interface control.
8. Install the new component. To install a new electronic control board or user
interface control, read the parts data sheet that comes with the part for the proper
installation process, and just reverse the disassembly procedure and reassemble.
Reinstall the console panel, and restore the electricity and gas supply to the dryer.
Make sure that the dryer is not in the service mode. Test the dryer operation. Make
sure to take the dryer out of the service test mode when the repair is completed.
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Dryer Motor
The dryer motor on most models is a dual-shaft, single-speed, .-horsepower, 1725 RPM
motor with an automatic thermal reset protector. One side of the motor shaft is threaded to
hold the blower wheel, and the opposite end of the shaft holds the belt pulley, which is
pressed onto the shaft. Inside the motor is a centrifugal switch, which serves three purposes.
It disengages the motor start winding when the motor reaches 75 percent of its rated speed,
it engages the run winding, and it also closes the circuit for the heater element. On other
models, there are dual motors (see Figure 20-2): one is dedicated to the drum and the other
one is dedicated to the blower assembly. The purpose of the dedicated motor for the blower
assembly is to be able to alter the blower wheel speed whenever necessary to optimize air
flow within the dryer.
The typical complaints associated with motor failure are:
. Fuse is blown or the circuit breaker trips.
. Motor will not start; it only hums.
. The dryer will not run.
. On electronic models, check for unusual display readouts and/or error codes.
To handle these problems, perform the following steps:
1. Verify the complaint. Verify the complaint by operating the dryer through its
cycles. Listen carefully, and you will hear if there are any unusual noises or if the
circuit breaker trips. On electronic models, turn off the electricity to the appliance
and wait for two minutes before turning it back on. If a fault code appears, look up
the code. If the dryer will not power up, locate the technical data sheet behind the
control panel or for diagnostics information. On some models you will need the
actual service manual for the model you are working on to properly diagnose the
dryer. The service manual will assist you in properly placing the dryer in the service
test mode for testing the dryer functions.
2. Check for external factors. You must check for external factors not associated with
the appliance. Is the appliance installed properly? Does the appliance have the
correct voltage? The voltage at the receptacle is between 108 volts and 132 volts
during a load on the circuit. Do you have the correct polarity? (See Chapter 6.)
3. Disconnect the electricity. Before working on the dryer, disconnect the electricity.
This can be done by pulling the plug from the electrical outlet. Or disconnect the
electricity at the fuse panel or at the circuit breaker panel. Turn off the electricity.
WARNING Some diagnostic tests will require you to test the components with the power turned on.
When you disassemble the control panel, you can position it in such a way that the wiring will
not make contact with metal. This act will allow you to test the components without electrical
mishaps.
4. Think safety. Shut off the gas supply. As a precaution before you begin servicing
the dryer, shut off the supply of gas to the dryer. The shutoff valve should be within
6 feet of the gas appliance.
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5. Gain access to the motor. In order to gain access to the motor, the top must be
raised (see Figure 20-19) by removing the screws from the lint screen slot. Insert a
putty knife about 2 inches from each corner; then disengage the retaining clips and
lift the top. On some models, the top is held down with screws (see inset in Figure
20-19). Remove the screws and lift the top. Now the front panel of the dryer must be
removed (see Figure 20-20). To remove the top panel, insert a putty knife and
disengage the retaining clip (see Figure 20-20a).
On some models, the top panel is held in place with two screws. Figure 20-20b
shows the removal of the screws that hold the lower part of the front panel in place.
Next, remove the screws that hold the upper part of the front panel in place (see
Figure 20-20c), and then disconnect the door switch wires (label them). With the
front panel out of the way, you can now disconnect the drive belt (see Figure 20-21).
Push on the idler pulley to release the tension from the drive belt, and remove the
belt from the motor pulley. Grab the drum and remove it from the cabinet (see
Figure 20-22). On some models, you will have to remove the back panel because the
drum comes out through the rear of the cabinet.
6. Disconnect the motor wire leads. Disconnect the motor wire leads from the wiring
harness. Set the ohmmeter on R ~ 1. Figure 20-23 illustrates testing the motor
windings and the centrifugal switch for continuity. When testing for resistance on the
motor, test from the common wire lead to the run winding. Then test for resistance
from the common wire lead to the start winding. Next, test for resistance from the
start winding to the run winding. To test for a grounded winding in the motor, take
the ohmmeter probes and test from each motor wire lead terminal to the motor
housing. The ohmmeter will indicate continuity if the windings are grounded. If the
ohmmeter reading shows no resistance between the motor windings, then replace the
motor. If the motor checks out okay, then check the timer.
7. Remove the motor. To remove this type of motor, you must first disconnect the
blower assembly by holding the motor shaft stationary and then turning the
blower wheel to remove it from the rear of the motor shaft (see Figure 20-24).
Then remove the spring clamps that hold the motor in the motor bracket (see
Figure 20-25). On some models, the motor pulley must be removed (new motors
come without the pulley attached) by loosening the allen set screw.
8. Install the new motor. To install the new motor (see Figure 20-26), just reverse the
disassembly procedure and reassemble. Then reassemble the dryer in the reverse
order of its disassembly. Restore the electricity and gas supply to the dryer and test
the motor. Make sure to take the dryer out of the service test mode when the repair
is completed.
Drive Belt
The drive belt extends from the motor pulley, past the idler pulley, and around the perimeter
of the dryer drum. The tension on the belt is maintained by the idler pulley and driven by a
pulley attached to one end of the motor shaft.
The typical complaints associated with belt failure are:
. The drum will not turn.
. Dryer motor spins freely.
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. It smells like something is burning.
. On electronic models, check for unusual display readouts and/or error codes.
To handle these problems, perform the following steps:
1. Verify the complaint. Verify the complaint by operating the dryer through its
cycles. Listen carefully, and you will hear if there are any unusual noises. Then,
with the door open, press the door switch and start the dryer. The drum should
rotate. On electronic models, turn off the electricity to the appliance and wait for
two minutes before turning it back on. If a fault code appears, look up the code. If
the dryer will not power up, locate the technical data sheet behind the control
panel or for diagnostics information. On some models you will need the actual
service manual for the model you are working on to properly diagnose the dryer.
The service manual will assist you in properly placing the dryer in the service test
mode for testing the dryer functions.
2. Check for external factors. You must check for external factors not associated with
the appliance. Is the appliance installed properly? Does the appliance have the correct
voltage? The voltage at the receptacle is between 108 volts and 132 volts during a
load on the circuit. Do you have the correct polarity? (See Chapter 6.) Check for
foreign objects lodged between the drum and bulkhead, etc.
3. Disconnect the electricity. Before working on the dryer, disconnect the electricity.
This can be done by pulling the plug from the electrical outlet. Or disconnect the
electricity at the fuse panel or at the circuit breaker panel. Turn off the electricity.
4. Think safety. Shut off the gas supply. As a precaution before you begin servicing
the dryer, shut off the supply of gas to the dryer. The shutoff valve should be within
6 feet of the gas appliance.
WARNING Some diagnostic tests will require you to test the components with the power turned on.
When you disassemble the control panel, you can position it in such a way that the wiring will
not make contact with metal. This act will allow you to test the components without electrical
mishaps.
5. Gain access to the drive belt. To gain access to the drive belt, the top must be raised
(see Figure 20-19) by removing the screws from the lint screen slot. Then insert a
putty knife about 2 inches from each corner, disengage the retaining clips, and lift
the top. On some models, the top is held down with screws (see the inset in Figure
20-19). Remove the screws and lift the top. Now the front panel of the dryer must be
removed (see Figure 20-20). To remove the top panel, insert a putty knife and
disengage the retaining clip (see Figure 20-20a). As shown in Figure 20-20b, remove
the screws that hold the lower part of the front panel in place. Next, remove the
screws that hold the upper part of the front panel in place (see Figure 20-20c), and
then disconnect the door switch wires.
6. Remove the drive belt. To remove the drive belt on this type of dryer, you can
disconnect the belt (see Figure 20-21). Push on the idler pulley to release the tension
from the drive belt. Now remove the belt from the motor pulley and from around
the drum (see Figure 20-27). If the drive belt is broken, just remove the belt.
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7. Install a new drive belt. To install the new drive belt, just reverse the disassembly
procedure, and reassemble. Then reassemble the dryer in the reverse order of its
disassembly. Restore the electricity and gas supply to the dryer and test. Make sure
to take the dryer out of the service test mode when the repair is completed.
Door Switch
The door switch is a normally open switch wired in series with the dryer motor. When the
dryer door is closed, the door switch contacts will close, completing the circuit through the
run winding of the drive motor. The door switch is located behind the front panel.
The typical complaints associated with switch failure are:
. Dryer will not operate at all.
. Dryer light does not work when the door is open.
. On electronic models, check for unusual display readouts and/or error codes.
To handle these problems, perform the following steps:
1. Verify the complaint. Verify the complaint by operating the dryer through its cycles.
Open the door to see if the light is working. On electronic models, turn off the
electricity to the appliance and wait for two minutes before turning it back on. If a
fault code appears, look up the code. If the dryer will not power up, locate the
technical data sheet behind the control panel or for diagnostics information. On
some models you will need the actual service manual for the model you are working
on to properly diagnose the dryer. The service manual will assist you in properly
placing the dryer in the service test mode for testing the dryer functions.
2. Check for external factors. You must check for external factors not associated with
the appliance. Is the appliance installed properly? Does the dryer have the correct
voltage supply? The voltage at the receptacle is between 108 volts and 132 volts
during a load on the circuit. Do you have the correct polarity? (See Chapter 6.)
3. Disconnect the electricity. Before working on the dryer, disconnect the electricity.
This can be done by pulling the plug from the electrical outlet. Or disconnect the
electricity at the fuse panel or at the circuit breaker panel. Turn off the electricity.
4. Think safety. Shut off the gas supply. As a precaution before you begin servicing
the dryer, shut off the supply of gas to the dryer. The shutoff valve should be within
6 feet of the gas appliance.
WARNING Some diagnostic tests will require you to test the components with the power turned on.
When you disassemble the control panel, you can position it in such a way that the wiring will not
make contact with metal. This act will allow you to test the components without electrical mishaps.
5. Gain access to the door switch. You must gain access to the door switch. On this
model, the top must be raised (see Figure 20-19) by removing the screws from the
lint screen slot. Then insert a putty knife about 2 inches from each corner, disengage
the retaining clips, and lift the top. On some models, the top is held down with
screws (see the inset in Figure 20-19). Remove the screws and lift the top.
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6. Test the door switch. The door switch is located in one of the upper corners of the
inside of the front panel (see Figure 20-34a). Once you have located the door switch,
disconnect the wires from the terminals. Set the ohmmeter on R ~ 1, attach the
probes of the ohmmeter to the terminals of the door switch, and then close the door.
With the door closed, there should be continuity. With the door open, the ohmmeter
should not show continuity. Some dryer models have a light inside the drum. This
light circuit is also part of the door switch circuitry. Three terminals are located on
the door switch. Take your ohmmeter probe and place it on the common terminal of
the door switch. To locate the common terminal, read the wiring diagram. It will
indicate which terminal is the common, which is the light, and which is for the
motor circuit. Take your probe and place it on the switch terminal (the light circuit);
then close the dryer door. The reading should indicate no continuity. Now open the
dryer door.you should have a continuity reading on the meter.
7. Remove the door switch. To remove the lever-type door switch (see Figure 20-34b),
remove the screws that hold the switch in place. Now lift the switch out from behind
the front panel. To remove the cylindrical type of door switch (see Figure 20-34c),
squeeze the retaining clips on the back side of the front panel, and pull out the
switch. To remove the hinge type of door switch (see Figure 20-34d), the front panel
must be removed. Next, remove the screws that hold the switch assembly in place.
8. Install the new door switch. To install the new door switch, reverse the disassembly
procedure, and reassemble. Reassemble the dryer, and install the wires on the new
switch terminals. Restore the electricity and gas supply to the dryer and test. Make
sure to take the dryer out of the service test mode when the repair is completed.
Thermostat
Thermostats can be mounted on the heater assembly (see Figure 20-2 and Figure 20-29)
and/or on the blower assembly (see Figures 20-2 and 20-35), or in the inlet filter screen (see
Figure 20-37). The thermostats monitor the air temperatures within the dryer drum, exhaust
vent, and the incoming air supply. The thermostats are bimetal switches that are automatic
reset, one-time use, or manual reset.
The typical complaints associated with thermostat failure are:
. The clothes are not drying.
. The dryer will not shut off.
. The dryer will not heat at all.
. The drying temperature is too high.
. Moisture retention (of fabrics) is unsatisfactory.
. On electronic models, an error code appears.
To handle these problems, perform the following steps:
1. Verify the complaint. Verify the complaint by operating the dryer through its
cycles. On electronic models, turn off the electricity to the appliance and wait for
two minutes before turning it back on. If a fault code appears, look up the code. If
the dryer will not power up, locate the technical data sheet behind the control panel
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C h a p t e r 2 1 : A u t o m a t i c G a s D r y e r s 721
or for diagnostics information. On some models you will need the actual service
manual for the model you are working on to properly diagnose the dryer. The
service manual will assist you in properly placing the dryer in the service test mode
for testing the dryer functions.
2. Check for external factors. You must check for external factors not associated with
the appliance. Is the appliance installed properly? Does the dryer have the correct
voltage supply? The voltage at the receptacle is between 108 volts and 132 volts
during a load on the circuit. Do you have the correct polarity? (See Chapter 6.) Is the
exhaust vent blocked?
3. Disconnect the electricity. Before working on the dryer, disconnect the electricity.
This can be done by pulling the plug from the electrical outlet. Or disconnect the
electricity at the fuse panel or at the circuit breaker panel. Turn off the electricity.
4. Think safety. Shut off the gas supply. As a precaution before you begin servicing
the dryer, shut off the supply of gas to the dryer. The shutoff valve should be within
6 feet of the gas appliance.
WARNING Some diagnostic tests will require you to test the components with the power turned on.
When you disassemble the control panel, you can position it in such a way that the wiring will
not make contact with metal. This act will allow you to test the components without electrical
mishaps.
5. Gain access to the thermostat. You must gain access to the thermostat through the
back on this model. Remove the screws from the back panel (see Figure 20-30). On
other models you will have to remove the drum to gain access to the thermostats.
6. Test the thermostat. To test the thermostat for continuity, remove the wires from the
thermostat terminals. With a continuity tester or an ohmmeter, test the thermostat
for continuity (see Figure 20-36). Do this to all of the thermostats in the dryer. On
some models, the thermostats might be located on the heater housing, behind the
drum, or in the lint screen opening (see Figure 20-37). If they all check out okay, then
reassemble the dryer and test for temperature operation. Note: Do not reinstall the
back panel at this point. Take a piece of paper and write down the temperature
ratings of the thermostats. These ratings are printed on the thermostats (L140, L290,
etc.) or on the wiring schematic. To test for temperature operation, you will need a
voltmeter and a temperature tester.
First, set up the instruments for testing the thermostatic operation. Take the
temperature tester thermocouple lead and insert it between the thermostat mounting
ear (see Figure 20-38) and the plate against which it mounts. Then connect the
voltmeter probes across the thermostat terminals. Use alligator clips attached to the
probe tips. This will allow you freedom of movement. Do not disconnect the wires
from the thermostat. Set the voltmeter range to AC voltage and the selector switch
on 300 volts. Remember: If there is more than one thermostat (in series with other
thermostats), the thermostats not under test must be electrically isolated and jumped
out with an insulated jumper wire with alligator clips attached. Review the wiring
schematic to determine which wires to remove and which ones to isolate and jump out.
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With the test meters in place, you are now ready to remove the exhaust vent duct
from the dryer. Seal off 75 percent of the exhaust opening from the dryer (see Figure
20-39). This will simulate a load of clothing in the dryer. On some models, you do
not have to block off the exhaust opening. Check the technical data sheet or the
service manual for the model you are servicing.
Restore the electricity and gas supply to the dryer. This test requires that the electricity
be turned on for its duration. Always be cautious when working with live wires. Avoid
getting shocked. Set the controls on the dryer to operate at a high heat. Turn on the
dryer and let it cycle. When the voltmeter is reading voltage, the thermostat has
opened. When there is no voltage reading on the voltmeter, the thermostat is closed.
As the dryer is cycling via the thermostat, record the temperature.
The thermostat should open at the preset temperature listed on the thermostat.
Table 20-1 illustrates the types of thermostats, along with their opening and closing
temperature settings. The temperature range of the thermostat should be within
}10 percent of the printed setting. If not, replace the thermostat.
CAUT ION Turn off the electricity and gas supply before replacing any parts of the dryer.
On some models, the thermostat will have four wires attached to it. Two wires are
for the bimetal switch contacts and the other two wires are for the bias heater. The
purpose of the bias heater is to apply a small amount of heat to the bimetal switch
contacts when the timer or fabric temperature switch is set to a lower temperature
setting. This will allow the bimetal switch contacts to open up sooner to maintain a
lower drum temperature. To test the bias heater, remove the wires from the thermostat,
set your multimeter to the ohms scale, and test across the bias heater terminals. The
resistance of the bias heater should be between 7000 and 28,000 ohms.
7. Replace the thermostat. Remove the screws that hold the thermostat in place. Replace
the thermostat with an exact replacement with the same temperature rating.
Reconnect the wires to their correct terminal positions. Then reverse the disassembly
procedure to reassemble the dryer, and test the thermostat.
8. Test the new thermostats. To test the new thermostats, repeat step 6. Restore the
electricity and gas supply to the dryer and test. Make sure to take the dryer out of
the service test mode when the repair is completed.
Thermistor
The thermistor (see Figure 20-2) monitors the incoming and outgoing air temperatures and
relays that information back to the electronic control board. Check the technical data sheet
for the location of the thermistors.
The typical complaints associated with thermistor failure are:
. The clothes are not drying.
. The dryer will not shut off.
. The dryer will not heat at all.
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C h a p t e r 2 1 : A u t o m a t i c G a s D r y e r s 723
. The drying temperature is too high.
. Moisture retention (of fabrics) is unsatisfactory.
. On electronic models, an error code appears.
To handle these problems, perform the following steps:
1. Verify the complaint. Verify the complaint by operating the dryer through its
cycles. On electronic models, turn off the electricity to the appliance and wait for
two minutes before turning it back on. If a fault code appears, look up the code.
If the dryer will not power up, locate the technical data sheet behind the control
panel or for diagnostics information. On some models you will need the actual
service manual for the model you are working on to properly diagnose the dryer.
The service manual will assist you in properly placing the dryer in the service test
mode for testing the dryer functions.
2. Check for external factors. You must check for external factors not associated with
the appliance. Is the appliance installed properly? Does the dryer have the correct
voltage supply? The voltage at the receptacle is between 108 volts and 132 volts
during a load on the circuit. Do you have the correct polarity? (See Chapter 6.) Is the
exhaust vent blocked?
3. Disconnect the electricity. Before working on the dryer, disconnect the electricity.
This can be done by pulling the plug from the electrical outlet. Or disconnect the
electricity at the fuse panel or at the circuit breaker panel. Turn off the electricity.
4. Think safety. Shut off the gas supply. As a precaution before you begin servicing
the dryer, shut off the supply of gas to the dryer. The shutoff valve should be within
6 feet of the gas appliance.
WARNING Some diagnostic tests will require you to test the components with the power turned on.
When you disassemble the control panel, you can position it in such a way that the wiring will
not make contact with metal. This act will allow you to test the components without electrical
mishaps.
5. Gain access to the thermistor. To gain access to the thermistor on this model, you
will have to remove the top panel, control panel (see Figure 20-40), front panel (see
Figure 20-41), and dryer drum (see Figure 20-2).
6. Test the thermistor. To test the thermistor for resistance, remove the wires from the
thermistor terminals. Set your multimeter on the ohms scale and place the test leads
on the thermistorfs terminals. Match the reading to the technical data sheet or the
service manual values. If you are reading an open or infinity, replace the thermistor.
Another way to test the thermistor is by placing the dryer into the service mode.
On some models, the thermistor might be located on the heater housing, behind the
drum, or in the lint screen opening (see Figures 20-2 and 20-37). If they all check out
okay, then reassemble the dryer and test for temperature operation.
7. Replace the thermistor. Remove the screws that hold the thermistor in place.
Replace the thermistor with an exact replacement with the same temperature rating.
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Reconnect the wires to their correct terminal positions. Then reverse the disassembly
procedure to reassemble the dryer, and test the thermistor.
8. Test the new thermistor. To test the new thermostats, repeat step 6. Restore the
electricity and gas supply to the dryer and test. Make sure to take the dryer out of
the service test mode when the repair is completed.
Start Switch
The start switch is a rotary or push button momentary contact switch used to start the dryer
and to energize the start winding in the drive motor. This switch is located in the control
panel on the dryer. The dryer door must be closed for the dryer to operate. If and when the
dryer door is opened, the start switch must be turned on to restart the dryer operation.
The typical complaints associated with the start switch are:
. The dryer will not start.
. On electronic models, check for unusual display readouts and/or error codes.
To handle these problems, perform the following steps:
1. Verify the complaint. Verify the complaint by operating the dryer. Before you
change the start switch, check the other components that are in the start circuit. On
electronic models, turn off the electricity to the appliance and wait for two minutes
before turning it back on. If a fault code appears, look up the code. If the dryer will
not power up, locate the technical data sheet behind the control panel for the
diagnostics information. On some models you will need the actual service manual
for the model you are working on to properly diagnose the dryer. The service
manual will assist you in properly placing the dryer in the service test mode for
testing the dryer functions.
2. Check for external factors. You must check for external factors not associated with the
appliance. Is the appliance installed properly? Does it have the correct voltage? The
voltage at the receptacle is between 108 volts and 132 volts during a load on the circuit.
Do you have the correct polarity? (See Chapter 6.) Check the fuses or circuit breaker.
3. Disconnect the electricity. Before working on the dryer, disconnect the electricity.
This can be done by pulling the plug from the electrical outlet. Or disconnect the
electricity at the fuse panel or at the circuit breaker panel. Turn off the electricity.
4. Think safety. Shut off the gas supply. As a precaution before you begin servicing
the dryer, shut off the supply of gas to the dryer. The shutoff valve should be within
6 feet of the gas appliance.
WARNING Some diagnostic tests will require you to test the components with the power turned on.
When you disassemble the control panel, you can position it in such a way that the wiring will not
make contact with metal. This act will allow you to test the components without electrical mishaps.
5. Remove the console panel to gain access. Begin by removing the console panel to
gain access to the start switch. With this type of dryer, remove the screws from the
console (see Figure 20-14a). On some models, the console will be able to lie flat
(see Figure 20-14b).
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6. Test the start switch. Remove the wires from the start switch terminals. Set the
ohmmeter on R ~ 1. Begin testing the start switch for continuity by placing one
probe of the ohmmeter on the common terminal (C) of the switch; then connect the
other probe to the normally open (NO) terminal. There should be no continuity.
With the ohmmeter probes attached to the switch, press the start switch button. You
should have continuity (see Figure 20-42). If the switch fails the test, replace it.
7. Remove the start switch. To remove the start switch, pull the knob off the switch
stem, remove the start switch mounting screws, and remove the switch.
8. Install a new start switch. To install a new start switch, just reverse the disassembly
procedure, and reassemble. Replace the wires on the switch. Reinstall the console
panel, and restore the electricity and gas supply to the dryer and test. Make sure to
take the dryer out of the service test mode when the repair is completed.
Temperature Selector Switch
The temperature selector switch is located in the console panel. This switch allows the
consumer to select different temperature settings for drying.
The typical complaints associated with the temperature selector switch are:
. Inability to select a certain temperature setting.
. No heat.
. The switch is stuck.
. On electronic models, check for unusual display readouts and/or error codes.
To handle these problems, perform the following steps:
1. Verify the complaint. Verify the complaint by operating the dryer through its
cycles. Before you change the temperature selector switch, check the other
components controlled by this switch. On electronic models, turn off the electricity
to the appliance and wait for two minutes before turning it back on. If a fault code
appears, look up the code. If the dryer will not power up, locate the technical data
sheet behind the control panel or for diagnostics information. On some models you
will need the actual service manual for the model you are working on to properly
diagnose the dryer. The service manual will assist you in properly placing the dryer
in the service test mode for testing the dryer functions.
2. Check for external factors. You must check for external factors not associated with
the appliance. Is the appliance installed properly? Does it have the correct voltage?
The voltage at the receptacle is between 108 volts and 132 volts during a load on the
circuit (see Chapter 6).
3. Disconnect the electricity. Before working on the dryer, disconnect the electricity to
it. This can be done by pulling the plug from the electrical outlet. Or disconnect the
electricity at the fuse panel or at the circuit breaker panel. Turn off the electricity.
4. Think safety. Shut off the gas supply. As a precaution before you begin servicing
the dryer, shut off the supply of gas to the dryer. The shutoff valve should be within
6 feet of the gas appliance.
726 P a r t V I : A p p l i a n c e S e r v i c e , I n s t a l l a t i o n , a n d P r e v e n t i v e M a i n t e n a n c e P r o c e d u r e s
WARNING Some diagnostic tests will require you to test the components with the power turned on.
When you disassemble the control panel, you can position it in such a way that the wiring will
not make contact with metal. This act will allow you to test the components without electrical
mishaps.
5. Gain access to the temperature selector switch. To access the temperature selector
switch, remove the console panel. On this type of dryer, remove the screws in the
console (see Figure 20-14a). On some models, the console will be able to lie flat (see
Figure 20-14b). On other models, your access is through the rear panel on the console.
6. Test the temperature selector switch. To test the temperature selector switch, locate
the selector switch circuit on the wiring diagram. Identify the terminals that are
regulating the temperature setting to be tested. Set the ohmmeter on the R ~ 1 scale.
Next, place the ohmmeter probes on those terminals. Then select that temperature
setting by either rotating the dial or by depressing the proper button on the switch
(see Figure 20-46). If the switch contacts are good, your meter will show continuity.
Test all of the remaining temperature settings on the temperature selector switch.
Remember to check the wiring diagram for the correct switch contact terminals
(those that correspond to the setting that you are testing).
7. Remove the temperature selector switch. To remove the temperature selector switch,
remove the screws that hold the switch to the console base, and remove the switch.
8. Install the new temperature selector switch. To install the new temperature selector
switch, just reverse the disassembly procedure and reassemble it. Then reattach the
wires to the switch terminals according to the wiring diagram. Reassemble the
console panel. Be sure when reassembling the console panel that the wires do not
become pinched between the console panel and the top of the dryer. Restore the
electricity and gas supply to the dryer and test. Make sure to take the dryer out of
the service test mode when the repair is completed.
Belt Switch
The belt switch is located on the drive motor baseplate (see Figure 20-47) and held in place
with two Phillips-head screws. The belt switch is activated by the movement of the idler
pulley assembly. If the belt breaks or comes off the pulley, the belt switch disconnects the
power to the motor, shutting down the dryer.
The typical complaints associated with the idler pulley are:
. The dryer will not run.
. The clothes are wet.
. On electronic models, check for unusual display readouts and/or error codes.
To handle these problems, perform the following steps:
1. Verify the complaint. Verify the complaint by operating the dryer through its cycles.
On electronic models, turn off the electricity to the appliance and wait for two minutes
before turning it back on. If a fault code appears, look up the code. If the dryer will not
power up, locate the technical data sheet behind the control panel or for diagnostics
information. On some models you will need the actual service manual for the model
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you are working on to properly diagnose the dryer. The service manual will assist you
in properly placing the dryer in the service test mode for testing the dryer functions.
2. Check for external factors. You must check for external factors not associated with
the appliance. Is the appliance installed properly? Does the dryer have the correct
voltage supply? The voltage at the receptacle is between 108 volts and 132 volts
during a load on the circuit (see Chapter 6).
3. Disconnect the electricity. Before working on the dryer, disconnect the electricity.
This can be done by pulling the plug from the electrical outlet. Or disconnect the
electricity at the fuse panel or at the circuit breaker panel. Turn off the electricity.
4. Think safety. Shut off the gas supply. As a precaution before you begin servicing
the dryer, shut off the supply of gas to the dryer. The shutoff valve should be within
6 feet of the gas appliance.
WARNING Some diagnostic tests will require you to test the components with the power turned on.
When you disassemble the control panel, you can position it in such a way that the wiring will not
make contact with metal. This act will allow you to test the components without electrical mishaps.
5. Gain access to the belt switch. To gain access to the belt switch, in this type of
dryer, remove the top panel, insert a putty knife, and disengage the retaining clip
(see Figure 20-20a).
6. Remove the idler pulley. Before removing the belt switch, you must first remove the
idler pulley and drive belt. To disconnect the belt on this model (see Figure 20-21),
push on the idler pulley to release the tension from the drive belt. Now remove the
belt from the motor pulley and from around the idler pulley. If the drive belt is
broken, just remove the belt. Next remove the two Phillips-head screws from the
belt switch (see Figure 20-47).
7. Testing the belt switch. Remove the two wires from the belt switch. Place your
multimeter test leads on the terminals and turn your meter to the ohms scale. When
activating the belt switch, the meter reading will indicate continuity. When deactivating
the belt switch, the meter reading will indicate an infinity reading. If the meter
indicates infinity when the belt switch is activated and deactivated, replace the switch.
8. Install the new belt switch. To install the belt switch, just reverse the disassembly
procedure, and reassemble it. Reassemble the dryer in the reverse order of its
disassembly, and test it for proper operation. Restore the electricity and gas supply
to the dryer and test. Make sure to take the dryer out of the service test mode when
the repair is completed.
Burner Assembly
The heating system for a gas dryer is composed of four main components: the burner, the
ignitor, the flame sensor, and the gas valve. The burner assembly is located on the baseplate
of the dryer.
The typical complaints associated with the burner assembly are:
. Burner will not light.
. The burner goes on and off.
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. Soot buildup.
. The ignitor will not glow.
. The burner trips on the high-limit thermostat.
. On electronic models, check for unusual display readouts and/or error codes.
To handle these problems, perform the following steps:
1. Verify the complaint. Verify the complaint by operating the dryer through its
cycles. Then open the dryer door, and place your hand inside to see if it is warm in
the drum. On electronic models, turn off the electricity to the appliance and wait for
two minutes before turning it back on. If a fault code appears, look up the code. If
the dryer will not power up, locate the technical data sheet behind the control panel
or for diagnostics information. On some models you will need the actual service
manual for the model you are working on to properly diagnose the dryer. The
service manual will assist you in properly placing the dryer in the service test mode
for testing the dryer functions.
2. Check for external factors. You must check for external factors not associated with
the appliance. Is the appliance installed properly? Is the exhaust vent clogged?
Check the voltage and gas supply to the dryer. Does the dryer have the correct
voltage supply? The voltage at the receptacle is between 108 volts and 132 volts
during a load on the circuit (see Chapter 6).
3. Disconnect the electricity. Before working on the dryer, disconnect the electricity.
This can be done by pulling the plug from the electrical outlet. Or disconnect the
electricity at the fuse panel or at the circuit breaker panel. Turn off the electricity.
4. Shut off the gas supply. Before you begin servicing any gas components, shut off
the supply of gas to the dryer. The shutoff valve should be within 6 feet of the gas
appliance.
5. Gain access to the burner assembly. To gain access to the burner assembly, you
must remove the top panel (or lower panel or access panel). The panel is held in
place with two retaining clips or screws, depending on the model. Using a flatblade
screwdriver, insert it about 4 inches from each side (Figure 21-6). Depress the
clips, pull the panel toward you, and remove the panel.
FIGURE 21-6
To open the top panel,
insert a lat-blade
screwdriver, depress
the retaining clips,
and remove the panel.
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