APC IN ROW RD ACRD101 - Manual (Page 53)

45 InRow RD 10 kW Air Cooled Operation and Maintenance
Cooling unit does not
shut down on
command
• Drive voltage • 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
with building
management system
(BMS) port
• Improper connection • Confirm that the cooling unit is connected to the BMS port
and not to the Control port.
• Make sure that the wire polarity is correct.
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
communicating with
each other
• A-Link failure • 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.
Problem Possible Cause Corrective Action