APC ACRD101, ACRD100 manual Problem Possible Cause, Corrective Action

Problem Possible Cause Corrective Action

Cooling unit does not • Drive voltage shut down on

command

•Verify that there is a drive voltage entering the input of the cooling unit. You may use the available +12 V or +24 V. You must then also use the ground.

•Verify Customer Input Contact settings. See “Contacts” on page 17.

No communication	• Improper connection	• Confirm that the cooling unit is connected to the BMS port
with building		and not to the Control port.
management system		• Make sure that the wire polarity is correct.
(BMS) port		Using a DC voltmeter, test the signal with no transmissions in
		progress. Pin 2 should be greater than Pin 1 by at least 200
		mV. Measure the cooling unit with the cable disconnected,
		and then measure it again with the cable connected. If the
		signal is less than 200 mV, the cooling unit may be reverse-
		wired.
		• Make sure that every cooling unit has either two sets of wires
		in its connector or one set of wires and a 100-ohm resistor (a
		terminating resistor of 100 to 120 ohms).

Cooling units are not • A-Link failure communicating with

each other

•Verify the actual number of cooling units in the group matches the group number setting.

•Verify that the A-Link ports of every cooling unit have either two cables or one cable and a terminator.

•Confirm that the A-Link cables are connected to the A-Link ports and that a network cable is connected to the network port.

Output air is 17°C (62°F) and fans are running at a very high rate of speed.

•Upper or lower supply air sensor fault

•Either the upper or lower supply air temperature sensor has a fault. Verify that both supply air temperature sensors are installed and working properly.

InRow RD 10 kW Air Cooled Operation and Maintenance 45