APC ACRD200 Installation Manual download pdf (Page 49)

41InRow RD Fluid Cooled Operation and Maintenance

Fluid valve not responsive • Actuator not connected

properly

• Verify that the actuator is connected properly.

• Actuator and shaft not

rotating together

• Tighten the linkage screw on the actuator shaft.

• Rotary switch on the

bottom of the actuator is

set incorrectly

• Confirm that the rotary switch is pointing toward the front of

the cooling unit.

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 <

mA.

• Test the external equipment by bypassing the output contact.

• Verify Customer Output Contact settings. See “Contacts” on

page 12.

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

nearby. You must then also use the ground.

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

page 12.

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 every cooling unit has 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

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APC ACRD200 Installation Manual Page 49

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