Carrier 69NT40-561-300, Operation And Service Manual

Page: 109 / 174

6–1 T-365
SECTION 6
TROUBLESHOOTING
6.1 UNIT WILL NOT START OR STARTS THEN STOPS
Condition Possible Cause Remedy/Refer-
ence Section
No power to unit
External power source OFF Turn On
Start − Stop switch OFF or defective Check
Circuit breaker tripped or OFF Check
Autotransformer not connected Section 5.2.2
Loss of control power
Circuit breaker OFF or defective Check
Control transformer defective Replace
Fuse (F3A/F3B) blown Check
Start − Stop switch OFF or defective Check
Component(s) not operating
Evaporator fan motor internal protector open Section 7.14
Condenser fan motor internal protector open Section 7.8
Compressor internal protector open Section 7.8
High pressure switch open Section 6.7
Heat termination thermostat open Replace
Malfunction of current sensor Replace
6.2 UNIT OPERATES LONG OR CONTINUOUSLY IN COOLING
Condition Possible Cause Remedy/Refer-
ence Section
Container
Hot load Normal
Defective box insulation or air leak Repair
Refrigeration system
Shortage of refrigerant Section 7.3
Evaporator coil covered with ice Section 6.6
Evaporator coil plugged with debris Section 7.13
Air bypass around evaporator coil Check
Controller set too low Reset
Compressor service valves or liquid line shutoff valve par-
tially closed Open valves
completely
Dirty condenser Section 7.10.1
Compressor worn Section 7.8
Current limit (function code Cd32) set to wrong value Section 4.4.3
Economizer solenoid valve malfunction Section 7.17
Digital unloader valve stuck open Section 7.21.1
Electronic expansion valve Section 7.16.1