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Modern Refrigeration and Air Conditioning
The circuit capacity (wire size, etc.) is checked as
follows: If, at the instant of starting, the voltage at the
refrigerator outlet drops more than 10 V, the wiring in
the circuit is not heavy enough. A flicker in the lights
at the instant the refrigerator starts is a sure sign of a
poor electrical supply.
It is very important to ground the refrigerator. All
removable electrical parts, like fans, thermostats, and
timers, are already safety grounded. If the wall out-
let has a three-prong socket and the unit has a match-
ing power cord plug, there is grounding. Otherwise,
a wire must be attached between a metal part of the
cabinet and a good ground, such as a water pipe. The
type of plug used on the appliance’s power cord indi-
cates the voltage and grounding. Refer to Chapter 10,
Electrical Power, for more information about electrical
power, circuit design, grounding, and plug and recep-
tacle configurations.
Safety Note
Check for Ground
Always check for proper grounding in the outlet
box that supplies current to the unit being serviced.
A common method is to take a voltmeter reading from
the “live” wall receptacle connection to the receptacle
ground connection. A full voltage reading indicates that
the outlet is properly grounded, as shown in Figure 19-3.
19.1.3 Checking for Proper Ventilation
Since domestic refrigerators are air-cooled, proper
ventilation is very important. Yet, many kitchens are
C heck for Ground
A lways check f or proper grounding in the outlet
b ox that supplies current to the unit bein g serviced.
A common method is to take a voltmeter reading f rom
the “ live” wall receptacle connection to the receptacle
g round connection. A full voltage readin g indicates that
t h e out let i s proper ly grounded, as sh own i n Figure 19- 3 .
designed without adequate space for air movement
around the appliance. In these rooms, only refrigerator-
freezers with forced-draft condensers should be used.
The fans draw cool air in at the floor level and circulate
it over the condenser. The warm air is then exhausted
back into the kitchen at, or near, floor level. Nothing
should be placed in front of these openings to block
airflow.
On many domestic refrigerators, condensers are
mounted on the back. Some are protected by a shroud.
The shroud provides a chimney effect, increasing the
rate of airflow over the condenser. With this type of
condenser, air spaces must be provided at the bot-
tom, back, and top of the unit to ensure good air
circulation.
Many freezers and some refrigerators have hot-
wall condensers. For these units, at least 2″ (51 mm)
of space must be allowed between the refrigerator or
freezer cabinet and surrounding surfaces.
19.1.4 Starting a Refrigerator
After testing the wall outlet with a voltmeter to be
certain the correct electrical power is being supplied,
put the temperature control in the off position. Connect
the electrical cord to a wall outlet. Then, adjust the tem-
perature control to the middle of its range and make
sure the refrigerator runs before moving it into its final
position.
After a few hours of operation, check the ther-
mometer in the fresh foods (refrigerator) compartment.
Adjust the temperature control setting to the custom-
er’s requirements.
19.2 Diagnosing Symptoms
Refrigerators, like all machines, wear out or suf-
fer malfunctions. Just as a doctor analyzes a patient’s
symptoms to determine what is wrong, an HVACR
technician observes the symptoms of the refrigeration
system’s malfunction and performs test to determine
what is wrong with the system. It is extremely impor-
tant to work methodically when troubleshooting a
system.
19.2.1 Diagnosing a No-Start Condition
If the refrigerator does not start, make sure that
the electrical supply circuit is in good condition and
that the proper voltage is being delivered to the unit.
Open and close the doors to make sure that the interior
lights are functioning properly. If the interior lights fail
to turn on and off as the door opens and closes, look
for problems in the electrical supply circuit.
HZ
Off
A COM
Fused
10 A 600 V
HOLD MIN MAX RANGE
HZ
Ω
v
V Ω
V
A HZ
HZ V
HZ A
Neutral
Ground
Hot
Goodheart-Willcox Publisher
Figure 19-3. When checking a wall receptacle ground
terminal, the multimeter measures ac voltage between the
hot (live) wire and ground.