Airedale Condensing Units (CU) 3kW - 80kW - Manual (Page 22)

CUS 15 - 60 / HCU 20 – 30D
Condensing Units
Chiller & Condensing Units
Installation & Maintenance:Part No: 6259592 IM 07\14
22
Troubleshooting
GENERAL
FAULT POSSIBLE CAUSE REMEDY / ACTION
Compressor not operating. No power to compressor Check isolator, fuses, MCBs, contactor and
control circuit wiring
Low pressure switch operated (large or
complete loss of refrigerant charge). Recover refrigerant, repair, evacuate and
recharge system.
Compressor thermal protection device
operated Check if compressor overheated - possibly
short of refrigerant
Condenser fan thermal trip open circuit Investigate and correct.
Seized compressor, possibly due to lack of
oil. Replace compressor - investigate oil
trapping and general installation.
Defective compressor motor. Check winding resistances - replace
compressor. If burnt out follow burn out
procedure using suction line burn-out drier.
Noisy Compressor. Lack of oil. Repair leaks if any, add oil if required but
not too much - remember too much is as
bad as too little. Investigate pipe system
and trapping.
Best method to pump down to see if oil can
be encouraged back. If no oil still, drain
compressor and measure in correct
quantity.
Expansion valve stuck in open position
(abnormally cold suction line). Ensure feeler bulb is tight on suction and
superheat is correct (normally 5
° C to 6
° C.). Replace power assembly or valve as
necessary.
Worn or scored compressor bearing.
(excessive knocking). Replace compressor.
Head Pressure too high. Condenser coil clogged or dirty. Clean condenser.
Air or other non-condensable gas in
system. Evacuate system and re-charge with new
refrigerant.
Overcharge of refrigerant. Remove excess refrigerant from system by
recovery system.