Carrier 69NT40-511-300 Operation And Service page 66

CONDITION
5.3 UNIT RUNS BUT HAS INSUFFICIENT COOLING
Compressor
Refrigeration System Refrigeration System
5.4 UNIT WILL NOT HEAT OR HAS INSUFFICIENT HEATING
No operation of any kind No operation of any kind
No control power No control power
Unit will not heat or has insuffi- Unit will not heat or has insuffi-
cient heat
5.5 UNIT WILL NOT TERMINATE HEATING
Unit fails to stop heating Unit fails to stop heating
5.6 UNIT WILL NOT DEFROST PROPERLY
Will not initiate defrost Will not initiate defrost
automatically i ll
Will not initiate defrost Will not initiate defrost
manually
Initiates but relay (DR) drops
out
Initiates but does not defrost Initiates but does not defrost
T-285
POSSIBLE CAUSE
Compressor valves defective
Abnormal pressures
Controller malfunction
Evaporator fan or motor defective
Suction modulation valve malfunction
Condenser Pressure Transducer defective
Shortage of refrigerant
Start-Stop switch OFF or defective
Circuit breaker OFF or defective
External power source OFF
Circuit breaker or fuse defective
Control Transformer defective
Evaporator fan internal motor protector open
Heat relay defective
Heater termination switch open
Heater(s) defective
Heater contactor or coil defective
Evaporator fan motor(s) defective or rotating backwards
Evaporator fan motor contactor defective
Controller malfunction
Defective wiring
Loose terminal connections
Low line voltage
Controller improperly set
Controller malfunction
Heater termination thermostat remains closed along with
the heat relay
Defrost timer malfunction (Cd27)
Loose terminal connections
Defective wiring
Defrost temperature sensor defective or heat termination
thermostat open
Heater contactor or coil defective
Manual defrost switch defective
Defrost temperature sensor open
Low line voltage
Heater contactor or coil defective
Heater(s) burned out
5-2
REMEDY/
REFERENCE
SECTION
6.8
5.7
5.9
6.16
6.18
Check
6.7.1
Check
Check
Turn ON
Replace
Replace
6.16
Check
6.15
6.15
Replace
6.15/6.16
Replace
5.9
Replace
Tighten
2.3
Reset
5.9
6.15
Table 3-5
Tighten/
Replace
Replace
Replace
Replace
4.10.4
2.3
Replace
6.15