Carrier WEATHERMASTER III 38HQ - Manual (Page 18)

TROUBLESHOOTING GUIDE — HEATING
SYMPTOM AND PROBABLE CAUSE
NO HEATING (Compressor Will Not Run)
1. Main power circuit open due to faulty power
supply.
2. Control power circuit open or faulty.
3. Defrost control malfunctioning.
4. Signal-Loc™ malfunction.
INSUFFICIENT HEATING (Compressor Runs or
Cycles)
1. Low suction and low head pressure due to
coil obstruction in airflow or refrigerant circuit.
2. High suction, low superheat.
3. Frozen outdoor coil.
4. Accessory electric resistance heaters not
operating.
5. High suction, low head pressures (caused by
refrigerant system or indoor fan problem).
6. Low suction, high head pressures (may be
accompanied by low airflow at air outlets).
7. Compressor no. 2 fails to start due to failure of
outdoor thermostat.
PROBABLE REMEDY
1
.
Check power supply, main power wire connec­
tions, fuses. See Electrical Data.
2. Check low voltage transformer, remote control
center, control relay and contacts, timer relay and
motor, compressor overloads and pressurestats
for faulty operation. Review component headings
in Service section. Check unit label diagram(s).
3. Check Defrost control procedure to be sure defrost
thermostat and relay are operational.
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 coil for obstruction (dirt, debris). Check that
outdoor air fan is correctly positioned and turns
freely. Review fan clearance requirements and
coil cleaning procedure. Check liquid line drier,
AccuRater.
2. Check refrigerant flow device Check refrigerant
charge.
3. Check fan operation, coil cleanliness. Check
defrost control circuit. Check refrigerant charge
(use Charging Charts and/or Operational Check
Charts).
4. Check heater power supply, outdoor thermostats
and their settings Check that heater elements are
not broken.
5. Reversing valve may be leaking or "hung-up "
Check valve and its solenoid for correct operation
Replace if suspect
Indoor fan motor capacitor may be defective
Replace capacitor Fan may be cycling on over­
loads. Check overloads, loose terminal connec­
tions Fan motor may be burned out. Check and
replace or lubricate See Fan Adjustment. Replace
or repair motor or fan as necessary.
6. Check for restricted refrigerant system com­
ponent. Check Heating Operational Check charts
to detect even charge. Check system for non­
condensables. Refer to Standard Service Tech­
niques Manual, Chapter 1, Refrigerants.
7 Check outdoor ambient switch. Switch should be
closed when ambient is below switch set point.
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