Carrier 69NT40-489-100 Series, Operation And Service Manual

Page: 78 / 178

54 T-305
CONDITION POSSIBLE CAUSE
REMEDY/
REFERENCE
SECTION
5.3 UNIT RUNS BUT HAS INSUFFICIENT COOLING
Compressor Compressor valves defective 6.8, page 61
Refrigeration System
Abnormal pressures 5.7, page 55
Controller malfunction 5.9, page 55
Evaporator fan or motor defective 6.16, page 70
Suction modulation valve malfunction 6.18, page 71
Condenser Pressure Transducer defective Check
Shortage of refrigerant 6.7.1, page 60
5.4 UNIT WILL NOT HEAT OR HAS INSUFFICIENT HEATING
No operation of any kind
Start-Stop switch OFF or defective Check
Circuit breaker OFF or defective Check
External power source OFF Turn ON
No control power
Circuit breaker or fuse defective Replace
Control Transformer defective Replace
Evaporator fan internal motor protector open 6.16, page 70
Heat relay defective Check
Heater termination switch open 6.15, page 70
Unit will not heat or has insuffi-
cient heat
Heater(s) defective 6.15, page 70
Heater contactor or coil defective Replace
Evaporator fan motor(s) defective or rotating backwards
6.16, page 70
6.17, page 71
Evaporator fan motor contactor defective Replace
Refrigeration Controller malfunction 5.9, page 55
Defective wiring Replace
Loose terminal connections Tighten
Low line voltage 2.3, page 12
5.5 UNIT WILL NOT TERMINATE HEATING
Unit fails to stop heating
Refrigeration Controller improperly set Reset
Refrigeration Controller malfunction 5.9, page 55
Heater termination thermostat remains closed along with
the heat relay
6.15, page 70
5.6 UNIT WILL NOT DEFROST PROPERLY
Will not initiate defrost
automatically
Defrost timer malfunction (Cd27)
Table 6, page
31
Loose terminal connections Tighten
Defective wiring Replace
Defrost temperature sensor defective or heat termination
thermostat open
Replace
Heater contactor or coil defective Replace
Will not initiate defrost
manually
Manual defrost switch defective Replace
Defrost temperature sensor open
4.10.4 , page
51
Initiates but relay (DR) drops
out
Low line voltage 2.3, page 12