American Power Conversion DX Manual De Usuario

Suction pressure too 
low

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

• Low refrigerant charge 

• Liquid line filter drier is blocked
• High evaporator superheat

• Clean evaporator coil.
• Check filters and replace as needed.
• Check for correct airflow setting.
• 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

• Check filter drier for excessive pressure drop.
• Check for proper superheat and TXV 

operation. 

System short of 
capacity

• Low refrigerant charge 

• Liquid line filter drier is blocked
• High evaporator superheat

• Insufficient air quantity across the 

evaporator coil

• Excessive outside air infiltration
• Lack of proper room vapor barrier

• Check subcooling and ensure it is at least 

10-15

°

F. Repair leak and recharge system.

• Check filter drier for excessive pressure drop.
• Check for proper superheat and TXV 

operation. 

• Check for correct airflow and clean filters.

• Reduce outside air infiltration.
• Install vapor barrier materials on floor, walls, 

and ceiling as needed.

Temperature control 
not tight enough

• Excessive outside air infiltration
• Lack of proper room vapor barrier

• Cool/reheat setpoints not close 

enough

• Reheat PID loop is not properly 

tuned

• Interstage delay is too large

• Return air temperature does not 

reflect actual room condition

• Reduce outside air infiltration.
• Install vapor barrier materials on floor, walls, 

and ceiling as needed.

• Check cooling and reheat setpoints and 

deadbands.

• Tune the PID loop for accurate reheat 

operation.

• Reduce the interstage delay to allow quicker 

response to temperature changes.

• Check for short cycling of cold supply air.
• Check air distribution for deficiencies.
• Consider using remote sensor control.

Note: Be certain to purchase the correct 
temperature and humidity probe. Check when 
ordering that your equipment is compatible.

Water carryover

• Dirt or oil residue on evaporator 

coil

• Insufficient air quantity across the 

evaporator coil

• Excessive airflow across the 

evaporator coil

• Blockage in condensate pan or 

drain line

• Low return air temperature

• High return humidity

• Excessive outside air infiltration
• Lack of proper room vapor barrier

• Clean the evaporator coil.

• Check for correct airflow and clean filters.

• Reduce airflow to specifications.

• Clean condensate pan and drain line.

• Verify the return air temperature is not below 

20ºC (68ºF).

• Check for short cycling of cold supply air
• Lower humidity setpoint.
• Check for short cycling of supply air
• Reduce outside air infiltration.
• Install vapor barrier materials on floor, walls, 

and ceiling as needed.