Carrier 69NT40-541-300, Operation And Service, Page: 86 / 152

5 − 2 T-318
CONDITION POSSIBLE CAUSE
REMEDY/
REFERENCE
SECTION
5.3 UNIT RUNS BUT HAS INSUFFICIENT COOLING
Compressor Compressor valves defective 6.8
Refrigeration System
Abnormal pressures 5.7
Controller malfunction 5.9
Evaporator fan or motor defective 6.16
Suction modulation valve malfunction 6.19
Condenser Pressure Transducer defective Check
Shortage of refrigerant 6.7.1
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
Heat relay defective Check
Heater termination switch open 6.15
Unit will not heat or has
insufficient heat
Heater(s) defective 6.15
Heater contactor or coil defective Replace
Evaporator fan motor(s) defective or rotating backwards 6.15/6.16
Evaporator fan motor contactor defective Replace
Controller malfunction 5.9
Defective wiring Replace
Loose terminal connections Tighten
Low line voltage 2.3
5.5 UNIT WILL NOT TERMINATE HEATING
Unit fails to stop heating
Controller improperly set Reset
Controller malfunction 5.9
Heater termination thermostat remains closed along with
the heat relay
6.15
5.6 UNIT WILL NOT DEFROST PROPERLY
Will not initiate defrost
automatically
Defrost timer malfunction (Cd27) Table 3-5
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 6.24
Initiates but relay (DR)
drops out
Low line voltage 2.3
Initiates but does not defrost
Heater contactor or coil defective Replace
Heater(s) burned out 6.15
Frequent defrost Wet load Normal