Specifications

74
The controller generates two types of alarms. Automatic
reset alarms will reset without any intervention if the condition
that caused the alarm corrects itself. Manual reset alarms
require the service technician to check for the alarm cause and
reset the alarm. The following method must be followed to
reset manual alarms:
Before resetting any alarm, first determine the cause of the
alarm and correct it. To reset the alarm, set R.ALM to YES.
The alarms will be reset. Indicator light will be turned off when
switched correctly. Do not reset the chiller at random without
first investigating and correcting the cause(s) of the failure.
Each alarm is described by a three or four-digit code. The
first one or two digits indicate the alarm source and are listed in
Fig. 58. The last two digits pinpoint the problem. See Table 50.
COMMAND REJECTED will be displayed if the unit is in
an ON state and a configuration chnage is attempted. Place the
unit in the OFF state before making a configuration change.
DIAGNOSTIC ALARM CODES AND POSSIBLE
CAUSES
Thermistor Failure
Alarm 1 — Cooler Fluid Entering (th.01)
Alarm 2 — Cooler Fluid Leaving (th.02)
Criteria for Trip — This alarm criterion is tested whether the
unit is on or off if the temperature as measured by the thermis-
tor is outside of the range –40 to 245 F (–40 to 118.3 C).
Action to be Taken — The unit shuts down normally, or is not
allowed to start.
Reset Method — Automatic, the alarm will reset once the
thermistor reading is within the expected range.
Possible Causes — If this condition is encountered, check the
following items:
• sensor wiring to the Main Base Board
• sensor accuracy
See the Thermistors section on page 60 for thermistor de-
scription, identifiers and connections.
Defrost Thermistor Failure
Alarm 3 — Circuit A (th.03)
Alarm 4 — Circuit B (th.04)
NOTE: Alarms 3 and 4 are not used or supported. If this condi-
tion is encountered, confirm machine configuration.
Thermistor Failure
Alarm 5 — Condenser Entering Fluid (th.06)
Criteria for Trip — This alarm criterion is tested whether the
unit is on or off if the temperature as measured by the thermis-
tor is outside of the range –40 to 245 F (–40 to 118.3 C).
Action to be Taken — If the unit is in the cool mode (Heat/
Cool Status = 0) no action will be taken. If the unit is a heat
machine (Unit Type = 4) and if the unit is in heat mode (Heat/
Cool Status = 1), then the machine shall continue to run, but a
default rise_per_%_unit_capacity_on of 0.1° F shall be used
by the capacity control function. Heating reset based on Delta
T (Heating Reset Select = 2) will be disabled.
Reset Method — Automatic, the alarm will reset once the
thermistor reading is within the expected range.
Possible Causes — If this condition is encountered, check the
following items:
• sensor wiring to the Main Base Board
• sensor accuracy
See the Thermistors section on page 60 for thermistor de-
scription, identifiers and connections.
Table 49 — Troubleshooting
LEGEND
SYMPTOM POSSIBLE CAUSE POSSIBLE REMEDY
Unit Does Not Run Check for power to unit • Check overcurrent protection device.
• Check non-fused disconnect (if equipped).
• Restore power to unit.
Wrong or incorrect unit configuration Check unit configuration.
Active alarm Check Alarm status. See the Alarms and Alerts section and follow
troubleshooting instructions.
Active operating mode Check for Operating Modes. See the Operating Modes section and follow trouble-
shooting instructions
Unit Operates too Long or
Continuously
Low refrigerant charge Check for leak and add refrigerant.
Compressor or control contacts welded Replace contactor or relay.
Air in chilled water loop Purge water loop.
Non-condensables in refrigerant circuit. Remove refrigerant and recharge.
Inoperative EXV • Check EXV, clean or replace.
• Check EXV cable, replace if necessary.
• Check EXV board for output signal.
Load too high Unit may be undersized for application
Circuit Does Not Run Active alarm Check Alarm status. See the Alarms and Alerts section and follow
troubleshooting instructions.
Active operating mode Check for Operating Modes. See the Operating Modes section and follow trouble-
shooting instructions.
Circuit Does Not Load Active alarm Check Alarm status. See the Alarms and Alerts section and follow
troubleshooting instructions.
Active operating mode Check for Operating Modes. See the Operating Modes section and follow trouble-
shooting instructions.
Low saturated suction temperature See Operating Modes 21 and 22.
High circuit suction superheat The circuit capacity is not allowed increase if circuit superheat is greater than 36 F
(20 C). See Alarms 74 and 75 for potential causes.
Low suction superheat The circuit capacity is not allowed to increase if the circuit superheat is less than
18° F (10° C). See Alarms 74 and 75 for potential causes.
Compressor Does Not Run Active alarm Check Alarm status. See the Alarms and Alerts section and follow
troubleshooting instructions.
Active operating mode Check for Operating Modes. See the Operating Modes section and follow trouble-
shooting instructions.
Inoperative compressor contactor • Check control wiring.
• Check scroll protection module.
• Check contactor operation, replace if necessary.
Chilled Water Pump is ON, but
the Machine is OFF
Cooler freeze protection Chilled water loop temperature too low. Check cooler heater.
EXV — Electronic Expansion Valve