American Power Conversion DX Benutzerhandbuch

Compressor fails to 
start

• Cooling mode disabled
• Cooling setpoint too high

• Compressor circuit breaker is 

tripped

• System is in alarm

• Head pressure alarm, high 

pressure switch is open

• Low suction pressure

• Compressor thermal overload is 

open

• Compressor failure

• Enable cooling mode.
• Adjust the cooling setpoint below the return 

air temperature by at least 4

°

F (2

°

C) to 

activate the compressor or compressors.

• Check the compressor windings and verify 

open or short to ground windings. Reset the 
circuit breaker and check the compressor 
contactor load side for proper voltage to the 
compressor.

• Check front panel display for active system 

alarms.

• For air cooled systems, check the condenser 

coil for air-obstructions, fan operation, and 
settings. Manually reset the high pressure 
switch.

• For water cooled systems, check the condenser 

water flow rate and water supply temperature. 
Check the pressure drop across the heat 
exchanger. Check and clean field installed 
strainers. Check the water regulating valve, 
actuator, and linkage for proper operation.

• For glycol cooled systems, check the fluid 

cooler coil for air obstructions and proper fan 
operation. Check the water flow rate and water 
supply temperature. Check the pressure drop 
across the heat exchanger. Check and clean 
field installed strainers. Check water 
regulating valve, actuator, and linkage for 
proper operation.

• Check for a restriction in the filter drier.
• Check for power at the liquid line solenoid 

coils. Check solenoid coil and valve operation.

• Check for proper TXV operation and 

superheat.

• Check refrigerant charge, check system for 

leaks.

• Verify the return air temperature is not below 

68

°

F.

• Check for low head pressure.
• Check compressor shell temperature. Check 

compressor for open windings and allow 
sufficient time for the compressor to cool 
down to room temperature. After the thermal 
overload resets, determine the cause of the 
failure.

• Determine the cause of failure and replace the 

compressor set.