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Appliance Repair Glossary

air shutter An adjustable shutter attached to the primary air openings of a burner used to

control the amount of primary air entering the burner.

aldehyde A class of compounds that can be produced from incomplete combustion of

gas fuels.

allen wrench An L-shaped tool that is used to remove hex screws.

alternating current (AC) Electrical current that flows in one direction and then reverses itself

and flows in the opposite direction. In 60-cycle current, the direction of flow reverses every 120th second.

ambient temperature Temperature of air that surrounds an object on all sides.

ammeter A test instrument used to measure current.

ampere The number of electrons passing a given point in one second.

armature The section of a motor that turns.

automatic defrost timer A device connected in an electrical circuit that shuts off the

refrigeration cycle and turns on the electric heaters to melt the ice off the evaporator coil.

bake element Lower heating element in an oven used for baking foods.

belt A band of flexible material used to transfer mechanical power from one pulley

to another.

bimetal (strip or thermostat) Two dissimilar metals joined together to form one unit with

a differential expansion rating. It will bend if there is a temperature change.

blower wheel A device attached to the indoor side of the fan motor shaft used to circulate

air across the evaporator coil.

bracket A hardened structure used to support a component.

broil element Upper heating element in an oven used for broiling foods.

BTU (British Thermal Unit) The amount of heat required to raise the temperature of one

pound of water one degree Fahrenheit.

burner A device in which an air and gas mixture has entered into the combustion zone

to be expelled and burned off.

burner head The portion of the burner past the outlet mixing tube that contains the

burner ports.

cabinet The outer wrapper of an appliance.

cam A rotating surface with rises and falls that open and close the switches in a timer.

capacitor A device that stores electricity; used to start and/or run circuits on many large

electric motors. The capacitor reduces line current and steadies the voltage supply while

greatly improving the torque characteristics of the fan motor or compressor.

capillary tube A metering device used to control the flow of refrigerant in a sealed system.

It usually consists of several feet of tubing with a small inside diameter.

Celsius The metric system for measuring temperature. The interval between the freezing

point and the boiling point of water is divided into 100 degrees. This is also called the

centigrade scale.

circuit A path for electrical current to flow from the power source to the point of use and

back to the power source.

circuit breaker A safety device used to open a circuit if that circuit is overloaded.

closed (circuit) An electrical circuit in which electrons are flowing.

combustion The rapid chemical reaction of a gas with oxygen to produce heat and light.

component An individual mechanical or electrical part of an appliance.

compressor An apparatus similar to a pump that is used to increase the pressure of

refrigerant that is to be circulated within a closed system.

condenser coil A component of the refrigeration system that transfers the heat that comes

from within a closed compartment to the outside surrounding area.

condenser fan A fan motor and fan blades used to cool the condenser coil.

contact points Two movable objects, or contacts, that come together to complete a circuit or

that separate and break a circuit. These contact points are usually made of silver.

continuity The ability of a completed circuit to conduct electricity.

control A device, either automatic or manual, that is used to start, stop, or regulate the flow

of liquid, gas, or electricity.

current The flow of electrons from a negative to a positive potential.

cycle A series of events that repeat themselves in the same order.

defective Refers to a component that does not function properly.

defrost cycle That part of the refrigeration cycle in which the ice is melted off the

evaporator coil.

defrost thermostat (heat pump AC models) A dual-purpose control that acts as an outdoor

thermostat and defrost control.

defrost timer A device used in an electrical circuit to turn off the refrigeration long enough

to permit the ice to be melted off the evaporator coil.

diagnosis The act of identifying a problem based on its signs and symptoms.

direct current (DC) Electric current that flows in one direction in a circuit.

end bell The end plates that hold a motor together.

energize To supply electrical current for operation of an electrical component.

evaporator coil A component of the refrigeration system that removes the heat from within

a closed compartment.

evaporator fan A motor and fan blades used to circulate the cold air.

Fahrenheit The standard system for measuring temperature. The freezing point of water is

32 degrees Fahrenheit, and the boiling point of water is 212 degrees Fahrenheit.

flashback Also known as extinction pop. Where the burner flames enter back into the

burner head and continue to burn after the gas supply has been turned off.

fuse A safety device used to open a circuit if that circuit is overloaded.

gasket A flexible material (either airtight or watertight) used to seal components together.

ground A connection to earth or to another conducting body that transmits current to earth.

ground wire An electrical wire that will safely conduct electricity from a structure to earth.

heat anticipator Used to provide better thermostat and room air temperature control.

Hertz (Hz) A unit of measurement for frequency. One hertz equals one cycle per second.

hot gas defrost A defrosting system in which hot refrigerant from the condenser coil

is directed to the evaporator coil for a short period of time to melt the ice from the

evaporator coil.

housing A metal or plastic casing that covers a component.

idler pulley A device that rests on or presses against a drive belt to maintain a specified

tension on it.

insulation Substance used to retard or slow down the flow of heat through a substance.

insulator A material that does not conduct electricity. It is used to isolate current-carrying

wires or components from other metal parts.

ladder diagram A wiring schematic in which all of the components are stacked in the form

of a ladder.

lead (wire) A section of electrical wiring that is attached to a component.

lint Fine pieces of cotton fiber that have broken away from a garment.

module A self-contained device with a group of interconnecting parts designed to do

a specific job.

nut driver A tool used to remove or reinstall hexagonal-head screws or nuts.

ohm A unit of measurement of electrical resistance.

ohmmeter A test instrument used for measuring resistance.

open (circuit) A break in an electrical circuit that stops the flow of current.

orifice An opening in a hood cap (orifice spud) through which a gas is discharged and

where the gas is metered.

overload protector A device that is temperature- , pressure- , or current-operated that is

used to open a circuit to stop the operation of that circuit should dangerous conditions arise.

parallel circuit Components that are parallel-connected across one voltage source. All of the

branches are supplied with the same amount of voltage.

port An opening in the burner head where the air and gas mixture is discharged and lit by

an ignition source.

pressure switch A device that is operated by pressure and turns a component on or off.

primary air The main air supply introduced into the burner which mixes with the gas before

it reaches the burner head.

PTC (positive temperature coefficient) A resistor that increases resistance (ohms) with

temperature increase.

pulley A wheel that is turned by or driven by a belt.

refrigerant A chemical substance used in refrigeration and air conditioning that produces

a cooling effect.

relay A magnetic switch that uses a small amount of current in the control circuit to operate

a component needing a larger amount of current in the operating circuit. A remote switch.

relief valve A safety device that is designed to open before dangerous pressure is reached.

resistance The opposition to current flow. The load in an electrical circuit.

run winding Electrical winding of a motor, which has current flowing through it during

normal operation of the motor.

safety thermostat A thermostat that limits the temperature to a safe level.

schematic diagram A line drawing that gives the electrical paths, layout of components,

terminal identification, color codes of wiring, and sometimes the sequence of events of an


series circuit A circuit in which all of the components are sequentially connected in the

same line. If one component fails, all the components fail.

short circuit An electrical condition in which part of a circuit errantly touches another part of

a circuit and causes part or all of the circuit to fail (and trip the circuit breaker or blow a fuse).

slinger ring A ring attached to the circumference of the condenser fan blade. The slinger

ring is positioned close to the base pan of the air conditioner so water in the base pan is

picked up by the rotating ring and dispersed into the hot condenser air stream where it


solenoid A cylindrical coil of insulated wire that establishes a magnetic field in the presence

of current.

start winding A winding in an electric motor used only during brief periods when the

motor is starting.

surface element The top cooking element on a range used for cooking foods.

switch A device to turn current on or off in an electrical circuit.

temperature A measure of heat energy or the relative lack thereof.

terminal A connecting point in a circuit to which a wire would be attached to connect

a component.

test light A light provided with test leads that is used to test electrical circuits.

thermistor A device that exhibits a large change in electrical resistance with a change in


thermometer A device used to measure temperature.

thermostat A device that senses temperature changes and that usually operates a control


thermostat (operating) A thermostat that controls the operating temperature of a component.

transformer A device that raises or lowers the main AC supply voltage.

venturi throat A section of the mixing tube body that narrows down and then flares

out again.

voltage The difference in potential between two points; the difference in static charges

between two points.

voltmeter A test instrument used to measure voltage.

VOM (voltohm-milliammeter) A test instrument used to measure voltage, resistance, and


water column (WC) A unit used for pressure. A one-inch water column equals a pressure

of 0.578 ounces per square inch.

watt A unit to measure electrical power.

wattmeter A test instrument used to measure electrical power.


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