APC ACRD101 User Manual

Controls erratic or 
inoperative

• Inlet temperature to cooling 

unit is higher than rated 
maximum temperature

• Reduce the load or add additional cooling equipment.

Fans fail to start

• Power supplies are not 

operating properly

• Confirm that the power supplies are seated properly and fully 

engaged. This is indicated by a green LED.

• Confirm that the cooling unit is plugged in and is receiving 

power. 

• Failed power supply

• Replace the power supply if the LED is red. 

• Cooling unit shutd own due to 

an external command

• Temporarily remove the user contact cable, if it is connected.

• Single fan fails to start

• Verify that the fan circuit breaker is 

O

N

.

Cooling unit cannot 
obtain setpoint

• Improper placement of remote 

temperature sensor

• Verify that the remote temperature sensor is properly located 

in the cold aisle.

• Dirty filter

• Clean the filter.

• Dirty coil

• Clean the coil.

• Application error

• For assistance, contact APC at a number on the back cover of 

this manual.

• Heat load is too far away

• Place the cooling unit closer to the heat load.

Water carryover

• Improper fan speed selected 

• RACS and HACS modes only. Select the next highest fan 

speed setting. For example, change the fan speed setting from 
Low to Med/Low. 

Temperature control 
not tight enough

• Improper placement of remote 

temperature sensor

• Verify that the remote temperature sensor is properly located 

in the cold aisle.

Water on outside of 
cooling unit

• Condensate drain hose is not 

connected or not properly 
routed outside the cooling unit

• Verify that the condensate drain hose is properly connected to 

the pump and properly routed outside of the cooling unit.

• Verify that the condensate drain line does not exceed 4.9 

meters (16 feet) lift and 15.4 meters (50.0 feet) horizontal run.

• Leak in piping system

• Locate and repair the leak.

• Cooling unit not leveled 

properly

• Adjust the leveling feet of the cooling unit.

• Damaged piping insulation

• Identify damaged area and repair the insulation.

Display interface not 
operational but 
cooling unit operates

• Display interface not 

connected properly

• Verify that the display interface cable is connected properly.

Incorrect air pressure • False filter clogs

• Verify that the ends of the clear plastic air tubes are not 

obstructed.

• Verify that the clear plastic air tubes are connected to the 

controller.

• Verify that the clear plastic air tubes are not pinched.

Alarms do not show 
up on monitoring 
equipment (Customer 
Output Contact)

• External monitoring equipment 

is not receiving power or is not 
functioning properly

• Confirm that power, if required, is being supplied to the 

external equipment.

• If the cooling unit (+12 V or +24 V) is providing power to the 

external equipment, verify that the external equipment is 
<50 mA.

• Test the external equipment by bypassing the output contact.
• Verify Customer Output Contact settings. See “Contacts” on