American Power Conversion DX Manual De Usuario

Compressor noisy

• Compressor or compressors may 

be rotating in the wrong direction

• Liquid slugging

• High head pressure

• Verify the pressure differential across the 

suction and discharge for each compressor. If 
no differential is present, verify the correct 
phasing to each compressor.

• Check for low evaporator superheat.
• Check operation of crankcase heaters.
• Verify liquid line solenoid valves close tightly 

during the off cycle. Check for obstructions 
which may prevent the valve from closing.

• Check operating head pressure.

Controls erratic or 
inoperative

• Control transformer problem

• Loose or broken wiring
• Module configured incorrectly

• System is in alarm

• Check control transformers for proper input 

voltage.

• Check control transformer secondary voltage. 

Output should be within + or - 10% of rated 
output.

• Check wiring for loose or broken connections.
• Set module configuration according to 

nameplate and options selected.

• Check front panel display for active system 

alarm.

Evaporator coil ices

• Dirty or blocked evaporator coil
• Dirty or blocked air filters
• Low  airflow
• Low evaporator superheat
• Low return air temperature

• Low refrigerant charge

• Clean evaporator coil.
• Check filters and replace as needed.
• Check for correct airflow setting.
• Check superhear and adjust to 10-15

°

F.

• Verify the return air temperature is not below 

20ºC (68

°

F).

• Check for short cycling of cold supply air.
• Check subcooling and ensure it is at least 

10-15

°

F. Repair leak and recharge system.

Head pressure too 
high

• Air cooled condenser malfunction

• Condenser water regulating valve 

malfunction

• Overcharge of refrigerant
• Non-condensable in system

• Fluid cooler malfunction

• Fluid pump malfunction
• Low fluid flow

• Glycol concentration higher than 

40%

• Check and clean the condenser coil. Check 

condenser fan operation and settings.

• Check water regulating valve, actuator, and 

linkage for proper operation.

• Remove excess refrigerant from system.
• Recover refrigerant charge, evacuate system 

and recharge.

• Check and clean the fluid cooler coil. Check 

fluid cooler fan operation.

• Check pump operation.
• For water cooled systems, check the condenser 

water flow rate and water supply temperature. 
Check pressure drop across the heat 
exchanger. Check and clean field installed 
strainers.

• For glycol cooled systems, check the water 

flow rate and water supply temperature. Check 
pressure drop across the heat exchanger. 
Check and clean field installed strainers.

• Verify glycol concentration, reduce to 

maximum 40%.