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Malfunction
1.
2.
3.
4.
5.
6.
Compressor fails to start.
Suction pressure inadequate.
High discharge pressure.
Suction and discharge pressure low.
Compressor starts but fails on over-
load.
Little or no heating capacity.
Table 3-2. Troubleshooting
Probable cause
a.
b.
c.
d.
e.
f.
g.
h.
i.
Control circuit open and/or fuse
blown.
Circuit breaker contacts open.
Contact sof high pressure cutout
switch open.
Outdoor thermostat defective or
open.
Circuit breaker defective.
Wiring defective.
Compressor motor contactor defec-
tive.
Electrical heater contactor defec-
t i v e .
Phase
sequence
relay
contacts
open.
Filter or evaporator coil air restric-
tion.
Insufficient volume of air passing
through condenser coil.
Lack of refrigerant.
a.
b.
c.
a.
b.
High discharge pressure.
Suction pressure low.
Blower motor defective.
Defective heater, contactor, or cir-
cuits.
Air movement over the evaporator
insufficient.
Corrective action
a.
e.
f .
g.
h.
i.
Repair control circuit and replace
fuse.
Reset circuit breaker (para 3-29).
Press reset button.
Wait until the ambient tempera-
ture exceeds 50” F. If switch is
imperative replace switch (para
3-26).
Replace
circuit breaker (para
3-23)
3-23).
Replace contactor (para 3-32).
Replce electrical heater contactor
(para 3-32 ).
Interchange two wires to reverse
phase sequence (para 3-28). Re-
place relay if defective (para
3-28).
Clean filter and coil (para 3-9).
Service condenser coil and evaporator
coil (para 3-9 ).
Check sight glass for appearance of
bubbles. Report low refrigerant to
direct support maintenance.
a. Clean condenser coil (para 3-11).
Remove obstruction from grilles.
b. Service air conditioning filter
(para 3-7).
c. Replace blower motor (para 3-24).
a. Test and replace defective heater
and contractors. Check the wir-
ing circuits repair or replace as
necessary.
b. Service the air conditioning filter
(para 3-7). Adjust grilles for
maximum air flow.
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