![background image](http://html1.mh-extra.com/html/carrier/69nt40-511-310/69nt40-511-310_operation-and-service-manual_2563841064.webp)
5-1
T-296
SECTION 5
TROUBLESHOOTING
CONDITION
POSSIBLE CAUSE
REMEDY/
REFERENCE
SECTION
5.1 UNIT WILL NOT START OR STARTS THEN STOPS
External power source OFF
Turn on
No power to unit
Start-Stop switch OFF or defective
Check
No power to unit
Circuit breaker tripped or OFF
Check
Autotransformer not connected
4.2.2
Circuit breaker OFF or defective
Check
Loss of control power
Control transformer defective
Replace
Loss of control power
Fuse (F3) blown
Check
Start-Stop switch OFF or defective
Check
Evaporator fan motor internal protector open
6.16
Condenser fan motor internal protector open
6.11
Component(s) Not Operating
Compressor internal protector open
6.8
Component(s) Not Operating
High pressure switch open
5.7
Heat termination thermostat open
Replace
Low line voltage
Check
Compressor hums, but does not Single phasing
Check
Compressor hums, but does not
start
Shorted or grounded motor windings
6.8
Compressor seized
6.8
5.2 UNIT OPERATES LONG OR CONTINUOUSLY IN COOLING
Container
Hot load (Failure to Pre--cool)
Normal
Container
Defective box insulation or air leak
Repair
Shortage of refrigerant
6.7.1
Evaporator coil covered with ice
5.6
Evaporator coil plugged with debris
6.15
Evaporator fan(s) rotating backwards
6.15/6.16
Defective evaporator fan motor/capacitor
6.17
Air bypass around evaporator coil
Check
Refrigeration System
Controller set too low
Reset
Compressor service valves or liquid line shutoff valve par-
tially closed
Open valves
completely
Dirty condenser
6.10
Compressor worn
6.8
Current limit (function code Cd32) set to wrong value
3.3.5
Suction modulation valve malfunction
6.18
Downloaded from