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Table 10N — Other Problems/Malfunctions
Description/
Malfunction
Probable Cause/Remedy
Chilled Water/Brine
Temperature Too
High (Machine
Running)
Chilled water set point set too high. Access set point on LID and verify.
Capacity override or excessive cooling load (machine at design capacity). Check
LID status messages. Check for outside air infiltration into conditioned space.
Condenser temperature too high. Check for proper flow, examine cooling tower
operation, check for air or water leaks, check for fouled tubes.
Refrigerant level low. Check for leaks, add refrigerant, and trim charge.
Liquid bypass in waterbox. Examine division plates and gaskets for leaks.
Guide vanes fail to open. Use Control Test to check operation.
Chilled water control point too high. Access control algorithm status and check
chilled water control operation.
Guide vanes fail to open fully. Be sure that the guide vane target is released.
Check guide vane linkage. Check limit switch in actuator. Check that sensor is in
the proper terminals.
Chilled Water/Brine
Temperature Too
Low (Machine
Running)
Chilled water set point set too low. Access set point on LID and verify.
Chilled water control point too low. Access control algorithm status and check
chilled water control for proper resets.
High discharge temperature keeps guide vanes open.
Guide vanes fail to close. Be sure that guide vane target is released. Check chilled
water sensor accuracy. Check guide vane linkage. Check actuator operation.
Chilled Water
Temperature
Fluctuates. Vanes
Hunt
Deadband too narrow. Configure LID for a larger deadband.
Proportional bands too narrow. Either INC or DEC proportional bands should be
increased.
Loose guide vane drive. Adjust chain drive.
Defective vane actuator. Check through Control Test.
Defective temperature sensor. Check sensor accuracy.
Low Oil Sump
Temperature
While Running
(Less than 100 F
[38 C])
Check for proper oil level (not enough oil). Check for proper refrigerant level (too
much refrigerant).
At Power Up,
Default Screen
Does Not Appear,
‘‘Tables Loading’’
Message
Continually
Appears
Check for proper communications wiring on PSIO module. Check that the COMM1
communications wires from the LID are terminated to the COMM1 PSIO connec-
tion.