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Electric Appliance and Air Conditioner Parts

as hard as might be expected. Just keep in mind that an appliance or air conditioner is

simply a collection of parts, located inside a cabinet, coordinated to perform a specific

function (Figures 10-1a, 10-1b, 10-1c, 10-1d, and Figure 9-4). Before servicing an appliance or

air conditioner, you must know what these parts are and how they function.

The Switch

The switch is a mechanical device used for directing and controlling the flow of current in

a circuit. Simply put, the switch can be used for turning a component on or off (Figure 10-2).

Internally, the switch has a set of contacts that close, allowing the current to pass; when

opened, current is unable to flow through it. Built into the switch, a linkage mechanism

actuates these contacts inside of the closed housing (Figure 10-3).

Switches come in a wide range of sizes and shapes, and can be used in many different

types of applications (Figure 10-4). The voltage and amperage rating is marked on the

switch or on the mounting bracket for the type of service the individual switch was

designed to do. The switch housing is usually marked with the terminal identification

numbers that correspond to the wiring diagram. These identify the contacts by number:

normally open (NO) contacts, normally closed (NC) contacts, or common (COM) contacts.

Internally, the switch can house many contact points for controlling more than one circuit.

When a switch failure is suspected, remember that there are only three problems that

can happen to a switch:

When these problems arise, the switches are not repairable, and they should be replaced

with a duplicate of the original.

Broiler pans

Bake and broil

elements

Oven and panel

light bulbs

Thermostats

Indicator lights

Top burner elements

Dials

Selector switches

Infinite (top element)

switches

Self-cleaning

oven sensor

(a)

Power cord

Portable models

Faucet coupler

Model and serial

number plate

Lower spray arm

Filter

Heating element

Rinse agent dispenser

Control panel

Detergent dispenser

Float

(overflow protection)

Lower rack

Upper rack

Pump hose

Pumps

Drive belts

Water valves

Timer and

components

Switches

Agitators

Agitator caps

Agitator blocks

Bushing and

seal kits

Brake drum

Transmission

components

Solenoids

(c)

Door springs

Door gaskets

Latches

Drum seals

Timers

Drum support

bearings

Elements

and ignitor

components

Drum belts

Thermostats

Idler pulley

Support rollers

and glides

(d)

Pressure Switch

previously, but with one important exception: The pressure switch is actuated by a diaphragm

that is responsive to pressure changes (Figure 10-5). This switch can be found in washing

machines and in dishwashers, and it operates as a water level control. Other uses include

furnaces, gas heaters, computers, vending machines, sump pumps, and other low-pressure

applications. The pressure switch is not serviceable, and should be replaced with a duplicate

of the original.

Switch (closed)

Plug

Lamp Motor

light and motor are on. If the switch is open, the light and motor are off.

Mounting hole Silver switch

contacts

NO

NC

Terminals

Actuator

PART IV

Thermostat

common heat-sensing methods used in appliances and air conditioners are the bimetal and

the expansion thermostats (Figure 10-6).

Any change in temperature will cause it to deflect, actuating the switch contacts. When the

bimetal cools, the reverse action takes place.

attached to bellows. The liquid converts to a gas when heated and travels up the tube to the

bellows. This causes the bellows to expand, thus actuating the switch contacts. When the

gas cools, the reverse action occurs.

Thermostats are used in applications as diverse as gas and electric ranges, automatic

dryers, room air conditioners, irons, waterbeds, spas, and in heating and refrigeration units.

Electromechanical Timer

Although the timer is the most complex component in the appliance, don’t assume that it is

the malfunctioning part. Check all of the other components associated with the symptoms

as described by the customer.

􀀀




Projection

bar

Fill position

Electrical contacts

Diaphragm

Air tube

To dome

on washer

outer tub

Tension bar

FIGURE 10-5

Construction of a

pressure switch.

Expansion type

Bimetal type

PART IV

automatic dryers, and dishwashers. Most of these timers are not serviceable and should be

replaced with a duplicate of the original.

The timer assembly is driven by a synchronous motor in incremental advances. It controls

and sequences the numerous steps and functions involved in each cycle of an appliance

(Figure 10-9). The timer directs the on and off times of the components in an electrical circuit.

It consists of three components assembled into one unit: the motor, the escapement, and the

A solenoid is not a serviceable part and

should be replaced with a duplicate of the

original. These devices are manufactured in a

variety of designs for various load force and

operational requirements. Solenoids are found in

automatic washers and dryers, gas and electric

ranges, automatic dishwashers, refrigerators,

freezers, automatic ice machines, and in heating

and air conditioning units.

FIGURE 10-15

Construction of

a water valve.

FIGURE 10-14

The solenoid coil and

plunger. When the coil

is activated, the

plunger will be drawn

to the center of the

magnetic ield.

Water Valves

The water inlet valve controls the flow of water into an appliance, and is solenoid-operated

(Figure 10-15). When it is energized, water in the supply line will pass through the valve

body and into the appliance. Some of the different types of water inlet valves that are used

on appliances include:

refrigerators, undercounter appliances and ice machines.

and ice makers. Some dishwasher models also use dual water inlet valves. The inlet

side of the valve has a fine mesh screen to prevent foreign matter from entering the

valve. Some water valves also have a “water hammer” suppression feature built

into them.

Solenoid

Armature

Diaphragm

Inlet

Screen

Flow washer

Outlet

Drain valves (Figure 10-18) are used on some dishwasher and washing machine models

to control the drainage of the water in the tub and its expulsion into the sewage system of

the residence.

The water valve should not be serviced. Replace it with a duplicate of the original.

major appliances.

PART IV

Motors

The two major assemblies that form an electric motor are the rotor and the stator (Figure 10-19).

The rotor is made up of the shaft, rotor core, and (usually) a fan. The stator is formed from

steel laminations, stacked and fastened together so that the notches form a continuous

lengthwise slot on the inside diameter. Insulation is placed so as to line the slots; and then

coils, wound with many turns of wire, are inserted into the slots to form a circuit. The wound

stator laminations are pressed into, or otherwise assembled within, a cylindrical steel frame to

form the stator (Figure 10-20). The end bells, or covers, are then placed on each end of the

motor. One important function of the end bells is to center the rotor or armature accurately

within the stator to maintain a constant air gap between the stationary and moving cores

(Figures 10-19 and 10-21).

These coils of wire are wound in a variety of designs, depending upon the electrical

makeup of the motor. They provide two or more paths for current to flow through the stator

windings. When the coils have two centers, they form a two-pole motor; when they have

End bells

Stator Rotor

four centers, they form a four-pole motor. In short, the number of coil centers determines

the number of poles that a motor has (Figure 10-22).

Thermal protection in a motor is provided by a temperature-sensitive element, which

activates a switch. This switch will stop the motor if it reaches the pre-set temperature limit.

The thermal protector in a motor is a non-replaceable part, and the motor will have to be

replaced as a complete component. There are two types of thermal protection switches:

reduced.

the shaft.

Rotor

Counter weight

Stator

FIGURE 10-20

Stator and rotor

construction.

FIGURE 10-21

End bells position the

motor shaft in the

center of the stator.

PART IV

Several types of motors that are used for different types of applications include the

following:

ice cube makers, water softeners, and humidifiers. In addition, they are integral to

timers for automatic washers, automatic dryers, and dishwashers.

speeds. They are used for small fans and clocks.

often used in automatic washer and dryer drive motors.

hard-to-start applications, such as compressors and pumps.

applications—for example, air conditioner fans.

three-phase power is available.

and many other appliances.

washer models.

microwave models.

Figure 10-23 illustrates some of these motors. Appliance motors are not repairable, and

they should be replaced with a duplicate of the original.

Compressors

The compressor is an electric motor that drives a mechanical compression pump designed

to compress the refrigerant vapors and to circulate the refrigerant within a sealed system.

Domestic refrigeration and room air conditioners use a hermetic compressor. The electric

PART IV

motor and mechanical compression pump are sealed within the same housing (Figure 9-7),

and it is a non-serviceable part. If the compressor fails, it must be replaced with a duplicate

of the original by a certified technician. Two types of compressors are used in domestic

refrigeration and room air conditioners: reciprocating and rotary. For more information on

compressor construction, visit the following compressor manufacturer’s websites:

Capacitors

A capacitor is a device that stores electricity to provide an electrical boost for motor starting

(Figure 10-24). Most high-torque motors need a capacitor connected in series with the start

winding circuit to produce the desired rotation under a heavy starting load.

There are two types of capacitors:

the start relay and the start winding terminal of the motor. Start capacitors are used

for intermittent (on and off) operation.

operation while the motor is running (continuous operation). The purpose of the

run capacitor is to improve motor efficiency during operation.

rating is stamped on the side of the capacitor. A capacitor must be accurately sized to the

motor and the motor load. Always replace a capacitor with one having the same voltage

rating and the same (or up to 10 percent greater) microfarad rating. On larger capacitors,

the rating is stamped on the side. Also, watch out for the decimal point on some capacitors.

disconnect device is also known as a fail-safe.

Normal Fail-safe mode

(a) (b)

by numbering or are color-coded.

Capacitors are used in electrical circuits to perform the following:

pass in a circuit

Both run and start capacitors can be tested by means of an ohmmeter or a capacitor tester.

Testing a Capacitor

Before testing a capacitor, disconnect the electricity. This can be done by pulling the plug from

the electrical outlet. Be sure that you only remove the plug for the product you are working

on. Or, you can disconnect the electricity at the fuse panel or at the circuit breaker panel.

Some appliance or air conditioner models have the capacitor mounted on the motor,

and some are mounted to the cabinet interior in the rear of the machine. Access might be

achieved through the front or rear panel, depending on which model you are working on.

Do not touch the capacitor until it’s discharged.

Many capacitors are internally fused. If you are not sure, you can use a 20,000-ohm,

2-watt resistor to discharge the capacitor. Do not use a screwdriver to short out the capacitor.

By doing so, you will blow out the fuse in the capacitor and the capacitor will not work.

Safely use an insulated pair of pliers to remove the wires from the capacitor, and place the

resistor across the capacitor terminals. Set the ohmmeter on the highest scale, and place one

probe on one terminal and the other probe on the other terminal (Figure 10-25). Observe the

FIGURE 10-25

Placing ohmmeter test

leads on the capacitor

terminals.

PART IV

meter action. While the capacitor is charging, the ohmmeter will read nearly zero ohms for a

short period of time. Then the ohmmeter reading will slowly begin to return toward infinity.

If the ohmmeter reading deflects to zero and does not return to infinity, the capacitor is

shorted and should be replaced. If the ohmmeter reading remains at infinity and does not

dip toward zero, the capacitor is open and should be replaced.

When using a capacitor analyzer to test capacitors, it will show whether the capacitor is

“open” or “shorted.” It will tell whether the capacitor is within its microfarads rating, and

it will show whether the capacitor is operating at the proper power-factor percentage. The

instrument will automatically discharge the capacitor when the test switch is released.

Heating Elements

Most heating elements are made with a nickel-chromium wire, having both tensile strength

and high resistance to current flow. The resistance and voltage can be measured with a

multimeter to verify if the element is functioning properly. Heating elements are available

in many sizes and shapes (Figure 10-26). They are used for

Heating elements are not repairable, and they should be replaced with a duplicate of the

original.

Mechanical Linkages

The mechanical linkages are those devices (connecting rods, gears, cams, belts, levers, pulleys,

etc.) that are used on appliances and air conditioners in order to transfer mechanical energy

from one point to another. Figure 10-27, the automatic ice maker, is an excellent example of

this. Some other examples are:

turns the drum.

which turns the transmission gears, which performs the agitation or spin cycle.

cam, which actuates the switches and rotates the ice ejector.

Brass drive gear

Motor, ice maker drive

Ice maker

weigh switch shaft

Conductor

Shaft

Contact

ice level control Gear

ice maker drive

PART IV

Wires

The wiring, which connects the different components in an appliance or air conditioner, is

the highway that allows current to flow from point A to point B. Copper and aluminum are

the most common types of wires that are used in appliances. They are available as solid

or stranded. Wires are enclosed in an insulating sleeve, which might be rubber, cotton, or

one of the many plastics. Wires are joined together or to the components by:

Never join copper and aluminum wires together, because the two dissimilar metals will

corrode and interrupt the flow of current. The standard wire-gauge sizes for copper wire are

listed in Table 10-1. As the gauge size increases from 1 to 20, the diameter decreases and the

amperage capacity (ampacity) will decrease also (see Table 10-2).

How to Strip, Splice, Solder, and Install Solderless and Terminal

Connectors, and How to Use Wire Nuts on Wires

To strip the insulation off the wire, there are certain steps you need to follow. First, you

must have a good wire stripper (Figure 10-28). Now, place the wire in the proper sized slot

in the wire stripper and work the stripper back and forth until a cut is made in the entire

insulation. Do not damage any of the strands in a stranded wire or put a knick in a solid

wire; this will cause a weakness in the wire that may cause a break in the circuit in the nottoo-

distant future. To remove the insulation, hold the wire tight with one hand and use the

other hand to gently move the insulation back and forth until the cut breaks clean and the

unwanted insulation can be pulled off the wire (Figure 10-29). Next, taper the insulation

with a knife to increase the wire’s flexibility, because a straight cut in the insulation will

create a force that can cause a wire to break prematurely (Figure 10-30). Figures 10-31 and

10-32 illustrate the different methods of splicing single and stranded wires together.

To connect wires to screw terminals, the wire being attached at a screw terminal should

be connected so that the loop lies in the direction the screw turns (Figure 10-33). The wire

should loop the screw a little less than one full turn, but excessive loops around the screw

terminal are not recommended, as this could cause wire damage.

Here is a good guideline that you should practice for soldering wire splices (Figures 10-34,

10-35, and 10-36). First, the wire being soldered together should be bright and clean at the

point of connection. The connection point should be tight so that the solder can flow

between the joint and solidify without any wire movement. When soldering wires together,

the wires should be coated with an electric soldering paste of flux, and soldered so that the

solder melts and flows into every crevice of the spliced joint. After the soldered joint cools,

the entire splice area should be covered with a waterproof plastic tape or heat-shrink

covering to protect the joint from shorting out against the cabinet of the product.

When you have to attach a

solderless connector or wiring

terminal to a wire, you should

follow these guidelines. Solderless

connectors should be used

according to their color codes, and

a connector for a smaller-gauge

wire should never be used on a

heavier-gauge wire. The wire

connector might burn off the wire

and break the circuit. A screw-on

wire connector (also known as a

wire nut) works well on pigtail

splices (Figure 10-37).

When installing a crimp-on

connector (Figure 10-38), there

should not be a gap between the

insulation and the terminal

connector, and if there is a gap, a

plastic sleeve should be added to

cover the bare wire, or reinstall a

new connector if needed. Always

prevent wires from shorting out and

breaking the circuit, causing you to

have to return to the service call.

Circuit Protection Devices

Circuit protection devices are

important for appliances and air

conditioners. These devices will

protect the electrical circuits and

components from damage from too

much current flow. Each fuse

(Table 10-3) or circuit breaker

(Figures 10-39, 10-40, and 10-41)

must be rated for voltage and

current. Never replace a fuse or

circuit breaker with one that is not

correctly rated for the product.

Fuses and circuit breakers must be

able to do the following:

(too much current)

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