Carrier WEATHERMASTER III 38HQ - Manual (Page 17)

TROUBLESHOOTING GUIDE — COOLING
SYMPTOM AND PROBABLE CAUSE PROBABLE REMEDY
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COMPRESSOR WILL NOT RUN OR SHUTS
OFF — WILL NOT RESTART
Contactor open
1. Burned out transformer, open thermostat
circuit, open overload.
2. Power supply interrupted.
3. Power circuit is open due to loose electrical
connection, open compressor safety device.
Contactor or coil defective.
4. Signal-Loc™ malfunction.
Contactor Closed, or Closes then Opens
1. Compressor power is out, compressor motor is
burned out or internal overloads are open.
Timer circuit (clock or switch) is faulty.
2. Compressor stuck.
3. Control circuit open due to faulty low-voltage
transformer or defective control circuit
compartment.
COMPRESSOR RUNS BUT COOLING IS
INSUFFICIENT
1. Low suction pressure or incorrect superheat.
2. Restricted airflow due to dirty filters, duct
obstruction or indoor coil icing. Refrigerant
system obstructed. Filter-drier obstructed or
refrigerant flow is insufficient.
3. High suction pressure/low head pressure due
to open internal pressure relief, defective com­
pressor valves or faulty reversing valve.
4. High suction pressure/low superheat (com­
pressor may be flooding).
COMPRESSOR CYCLES ON AND OFF
1. Internal overloads are opening or refrigerant
system is dirty. High or low pressure switch is
opening.
2. Faulty timer or defrost control operation.
Run capacitor faulty.
3. Fan motors operate intermittently.
4. Reversing valve in mid-position.
1. Check control circuit component and wiring. Refer
to unit label diagram, check all safety devices.
Refer to Standard Service Techniques Manual,
Chapter 2, Electrical.
2. Check for blown fuses or tripped circuit breakers.
3. Check power wire connection for tightness. Check
compressor internal thermostat, overloads (see
label diagram). Check contactor, replace if
defective.
4. Check wire connections. Check continuity thru
terminals 2 and 3. Check to see if power wire has
been routed thru current loop.
1. Check main power supply and wiring. Refer to
Electrical Data table and label diagram. Check
defrost timer circuit relay. Check defrost control
contacts. Replace defective controls.
2. Check start capacitor. Check compressor motor
windings.
3. Review label diagrams. Check control power
wires, connections. Check control transformer
power output (24 v). Check remote control center
contacts and temperature settings.
1 Check Refrigerant Charging procedure, charging
charts. Check AccuRater™ for proper piston.
2. Check indoor air system for obstructions — dirty
filters, ductwork debris, improper fan speed.
Expansion valve or AccuRater improperly sized.
3. Check Carrier Compressor Service Manual for
compressor repair procedures. See Compressor
Removal. Check reversing valve solenoid opera­
tion and valve seats.
4. Check refrigerant flow device Check that maxi­
mum elevation between indoor and outdoor units
is not too great Check refrigerant charge
1. Check refrigerant system for noncondensables, or
improper charge. See Refrigerant Charging.
Check for airflow obstructions See Coil Cleaning.
2. Check timer or defrost control relays and con­
tacts. Replace fun capacitor.
3. Check motor leads and overloads.
4. Check reversing valve solenoid. See label diagram.
Check that dirt in refrigerant system does not
cause valve to "hang up."
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