Refrigeration & Air Conditioning Technology 7th Edition

Unit 45 Domestic Refrigerators and Freezers 1371
needs to be done is mount it, plug it in, and make certain
that the water line is connected to the refrigerator
as instructed. No field wiring is required to install the ice
maker, except for plugging it into the plug provided for
the wiring harness. The wiring diagram in Figure 45.109
shows an ice maker and where it is connected to the circuit.
Notice that there are no controls or switches external
to the component itself that will affect the operation of
the device.
45.10 SERVICING THE APPLIANCE
The technician should make every effort to separate problems
into definite categories. Some problems are electrical
and some are mechanical. It is also important to know the
type of appliance. For example, when servicing freezers,
the technician does not have to think about the fresh-food
compartment—only the low-temperature compartment.
Also, the type of box determines the type of service. For
example, a box that has a forced-draft evaporator will have
a fan motor that can be a source of problems.
Unit 5, “Tools and Equipment,” describes tools and
equipment used by technicians for the servicing of refrigeration
equipment. A poorly equipped technician works
at a disadvantage. Lack of proper instruments may prevent
discovery of the problem, and the customer’s equipment
or property can be damaged or the technician may
be injured if, for example, the correct equipment for moving
a refrigerated box is not used. A professional is well
equipped. The sections that follow address a number of
service-related issues regarding the domestic refrigerator
and freezer.
Electrical Problems
Electrical problems in a domestic refrigerator or freezer are
relatively easy to diagnose. This is because the appliance
has relatively few electrical loads and switches and all of
the components are located within its cabinet. In addition,
a complete wiring diagram is attached to the appliance,
usually on the back. Be sure to locate this very important
document before attempting to repair the unit. One very
important thing to know is the sequence of operations
for the particular unit being worked on. Knowing what
is supposed to happen when can save a lot of time when
troubleshooting the system. For example, if the compressor
and condenser fan motor are wired to cycle on and off
together, troubleshooting the problem will be a breeze if the
condenser fan is operating and the compressor is not. The
unit is being supplied with power because the condenser
fan motor is operating. Also, the cold control is closed and
operational because it is feeding power to the condenser fan
motor. It is not difficult to conclude that the problem lies
with the compressor, its wiring, or its associated starting
components.
Here are a few things to keep in mind when troubleshooting
the electrical circuits of a refrigerator or freezer:
• Have the wiring diagram handy.
• Observe what the appliance is doing and what it is not
doing.
• Observe what appliance components are operating and
those that are not.
• Know the sequence of operations of the appliance.
• Know the difference between a load (power-consuming
device) and a switch (power-passing device).
• Know how to correctly use a voltmeter and ohmmeter.
• When testing resistance or continuity, make certain that the
circuit power is disconnected and that the circuit or component
being tested is completely removed/disconnected
from the circuit to prevent false/feedback readings.
• When possible, unplug the appliance and discharge all
capacitors to reduce the risk of electric shock.
• Make certain all electrical connections are tight.
• Make certain that all electrical wires are as far away as
possible from wet locations, such as where condensate
may drip or accumulate.
• Make certain that all electrical wires are as far away as
possible from rotating components, such as fan motors.
• When replacing an electrical component, use an exact
replacement whenever possible.
Mechanical Problems
Mechanical problems in domestic refrigerators and freezers
often involve the refrigerant circuit and the compressor.
Mechanical problems include system leaks, system
undercharge, system overcharge, and compressor-related
issues. The sections that follow are geared toward the
mechanical portion of system evaluation and provide valuable
service-related procedures to properly identify and
remedy mechanical problems in the appliance.
CABINET PROBLEMS. In order for the refrigerant to correctly
circulate through the evaporator and condenser,
domestic refrigerators must be leveled according to the
manufacturer’s specifications. If it is not level, the ice maker
may overflow when filled with water, and condensate may
not completely drain during defrost. The leveling screws or
wheels are on the bottom of the box or cabinet. Leveling
feet may be adjusted with a wrench or a pair of adjustable
pliers. Wheels have leveling adjustments to raise and lower
them, Figure 45.112. If the floor is too low, spacers may
need to be added at the lowest point so that all four feet
or wheels are touching the floor or spacers, Figure 45.113.
Vibration may make the refrigerator noisy if all four points
do not touch with equal pressure. As well, rattling food containers,
which are often glass, can create a lot of sound on
the outside of the box, Figure 45.114. Also, if the box is
not level, the door or doors may not close correctly or may