Condensing Units
CU/CFCU
Condensing Units
23
Installation & Maintenance Manual : 6259626 IM V1.6.0 04/16
Troubleshooting
(CU./CUH. 1
– 4 Only)
FAULT
POSSIBLE CAUSE
REMEDY/ACTION
CRITICAL ALARMS:
Aux. Alarm (LED 3 On)
Auxiliary Trip.
Check operation of customer-added
alarm function.
Outdoor Fan Fault
(LED 1 & 2 On)
Fan Trip.
Check and (if necessary) replace fan.
Coil Sensor Fault
(LED 2 flashing 1 Hz)
Faulty Sensor.
Replace sensor.
No Cooling/Heating
(LED 4 flashing 1 Hz)
Compressor Protection Delay.
Wait for a maximum of 10 minutes then
re-check.
Head Pressure too high/HP
cut-out operated
(LED 2 On)
Condenser coil clogged or dirty.
Clean condenser.
Overcharge of refrigerant. Normally
troublesome in warm weather.
Remove excess refrigerant from system.
Air or other non-condensable gas in system. Evacuate system and re-charge with
new refrigerant.
Head pressure controller faulty.
Check fan speed controller - if faulty
- replace.
Fan not operating or operating inefficiently. Check motor - if faulty - replace.
Compressor short cycles or
LP cut-out operated (LED 1
On)
LP switch faulty (if fitted).
Check cut out pressure and replace
if necessary.
Dirty indoor unit filters.
Replace.
Dirty or icing evaporator (reduced airflow).
Defrost and/or clean. Check gas charge and
expansion valve.
Lack of refrigerant (bubbles in sight glass
only as indication).
Check for leaks - repair and
recharge system.
Clogged filter drier (pressure/temperature
drop across it).
Replace.
Condenser fan running at full speed in
winter (full airflow).
Check fan speed controller setting - if faulty -
replace.
Start up problems in very low ambients or
when long pipe runs are experienced.
Check for low suction pressures on start-up
and fit a low ambient start kit if required, or
check operation of system if already fitted.
