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5-5. Troubleshooting Chart
by a list of probable causes of the trouble. The
Troubleshooting procedures for direct and general
corrective action recommended is described op-
support maintenance are listed in Table 5-1. Each
posite the probable cause.
trouble symptom or malfunction stated is followed
Table 5-1. Troubleshooting Chart
Malfunction
1. Compressor will not start.
2. Compressor starts but goes out on
overload.
3. Little or no heating capacity.
4. Insufficient cooling.
5. Low suction pressure.
6. Low discharge pressure.
7. Low suction and discharge
pressure.
Probable Cause
a. Open control circuit.
b. Defective circuit breaker.
c. Defective starting relay or
capacitor (single phase com-
pressor.
d. Defective phase sequence relay
(three phase compressor).
e. Defective high or low pressure
cutout switch.
f. Defective compressor motor or
thermal protector.
a. Defective compressor run
capacitor (single phase com-
pressor).
b. Defective compressor.
a. Loose electrical connection or
faulty wiring.
b. Defective temperature selector
switch or mode selector switch.
c. Defective heaters.
d. Defective heater high temperature
cutout switch.
e. Defective heater relay.
f. Defective evaporator fan motor.
a. Low refrigerant charge.
b. Dehydrator clogged.
c. Pressure regulator valve defective.
d. Air in refrigerant system.
e. Thermal expansion valve defective.
f. Defective solenoid valve.
g. Defective quench thermal ex-
pansion valve.
a. l)efective thermal expansion valve.
b. Dehydrator clogged or defective.
c. Pressure regulating valve defective.
a. Compressor not pumping due to
defective compressor
b. Defective high-low condenser fan
thermostatic switch.
a. Lack of refrigerant.
b. Defective thermal expansion valve.
Corrective Action
a. Make continuity check of control
circuit (para 4-12).
b. Replace circuit breaker (para 4-50
through 4-54).
c. Replace defective capacitor or
relay (para 4-61).
d. Replace defective relay (para 4-50
thru 4-54).
e. Replace defective switch (para 5-
21).
f. Replace compressor (para 5-17).
a. Replace capacitor (para 4-61).
b. Replace compressor (para 5-17).
a. Check wiring and repair if
necessary (para 4-33).
b. Replace defective switch (para 4-
44 thru 4-48).
c. Replace defective heaters (para 4-
35).
d. Replace defective thermostatic
switch (para 4-34).
e. Replace defective heater relay
(para 4-50 thru 4-54).
f. Repair motor (para 6-8).
a. Charge refrigerant system (para 6-
3).
b. Replace clogged dehydrator (para
5-24).
c. Replace defective valve (para 5-
31).
d. Purge and charge system (para 6-
3).
e. Replace defective valve (para 5-
28).
f. Replace defective solenoid valve
(para 5-27).
g. Replace defective valve (para 5-
29).
a. Replace defective valve (para 5-
28).
b. Remove restriction or replace
dehydrator (para 5-24).
c. Replace defective valve (para 5-
31).
a. Replace defective compressor
(para 5-17).
b. Replace defective switch (para 4-
41).
a. Check sight glass for bubbles or
milky appearance and check
system for leaks (para 4-64).
Repair leaks and add refrigerant
as necessary.
b. Replace valve (para 5-28).
5-3
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