American Power Conversion Central Air Conditioning System Benutzerhandbuch

Controls are erratic 
or inoperative

• Incorrect secondary voltage.

• Ensure that the control transformer secondary 

voltage is within +/- 10% of 24 VAC.

• Remote shutdown input is 

cycling the Module on and 
off.

• Check the event log for an entry in the log that 

indicates remote shutdown activity.

Evaporator motor 
fails to start

• Control circuit breaker is 

tripped.

• Reset the control circuit breaker.

• Frequency Drive is in an 

alarm condition or has failed.

• Check the event log for a VFD alarm entry. 

Replace the frequency drive.

Humidifier 
inoperative

• Humidifier circuit breaker 

tripped.

• Water supply strainer may be 

clogged.

• Improper water supplied to 

humidifier.

• Non-essential lockout has 

been activated by a user-
defined input with the 
equipment.

• Check for short circuit. Reset the circuit breaker.

• Remove and clean the strainer.

• For proper operation, the humidifier requires a 

regular water supply. Any treated water 
(demineralized, softened, or ionized water) will 
result in improper humidifier operation.

• Review the event log to see if this alarm input has 

been activated.

Reheat elements 
inoperative

• Circuit breaker is open.

• Non-essential lockout has 

been activated by a user-
defined input with the 
equipment.

• Check for direct short circuits. Reset the circuit 

breaker.

• Review the event log to see if this alarm input has 

been activated.

Airflow too Low

• External static pressure is too 

high.

• The pressure drop across the 

chilled water coil is below 
the recommended value.

• Cooling setpoint is too low. 

• Try to compensate by increasing the blower speed 

to match recommended coil pressure drops.

• Raise the Module to the minimum height or add 

duct transitions to direct the air across the floor.

• Check the chilled water coil pressure drop through 

the display interface. Pressure should match 
recommended pressure drops indicated on the 
chart based on Module size. If the pressure drop is 
below the recommended settings, increase the 
blower speed until the pressure drop matches the 
recommended setting. See “Calibrate airflow 
manually” on page 17.

• Verify that the cooling setpoint is not below 68° F 

(20° C).