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Table 42 — Alarm and Alert Codes
ALARM/
ALERT
CODE
ALARM
OR
ALERT
DESCRIPTION
WHY WAS THIS
ALARM
GENERATED?
ACTION TAKEN
BY CONTROL
RESET
METHOD
PROBABLE
CAUSE
T051 Alert
Circuit A, Compressor 1
Failure
Compressor feedback signal
does not match relay state
Compressor A1 shut
down.
Manual
High-pressure switch open,
faulty CSB, loss of condenser
air, filter drier plugged, non-
condensables, operation
beyond capability.
A051 Alarm
Circuit A, Compressor 1
Failure
Respective current sensor
board (CSB) feedback signal
is ON when the compressor
should be off
Unit shut down Manual
Welded compressor contac-
tor, CSB wiring error.
T052 Alert
Circuit A, Compressor 2
Failure
Compressor feedback signal
does not match relay state
Compressor A2 shut
down.
Manual
High-pressure switch open,
faulty CSB, loss of condenser
air, filter drier plugged, non-
condensables, operation
beyond capability.
A052 Alarm
Circuit A, Compressor 2
Failure
Respective current sensor
board (CSB) feedback signal
is ON when the compressor
should be off
Unit shut down Manual
Welded compressor contac-
tor, CSB wiring error.
T055 Alert
Circuit B, Compressor 1
Failure
Compressor feedback signal
does not match relay state
Compressor B1 shut
down.
Manual
High-pressure switch open,
faulty CSB, loss of condenser
air, filter drier plugged, non-
condensables, operation
beyond capability.
A055 Alarm
Circuit B, Compressor 1
Failure
Respective current sensor
board (CSB) feedback signal
is ON when the compressor
should be off
Unit shut down Manual
Welded compressor contac-
tor, CSB wiring error.
T056 Alert
Circuit B, Compressor 2
Failure
Compressor feedback signal
does not match relay state
Compressor B2 shut
down.
Manual
High-pressure switch open,
faulty CSB, loss of condenser
air, filter drier plugged, non-
condensables, operation
beyond capability.
A056 Alarm
Circuit B, Compressor 2
Failure
Respective current sensor
board (CSB) feedback signal
is ON when the compressor
should be off
Unit shut down Manual
Welded compressor contac-
tor, CSB wiring error.
A060 Alarm
Cooler Leaving Fluid
Thermistor Failure
Thermistor outside range of
–40 to 245 F (–40 to 118 C)
Chiller shut down
immediately
Automatic
Thermistor failure, damaged
cable/wire or wiring error.
A061 Alarm
Cooler Entering Fluid
Thermistor Failure
Thermistor outside range of
–40 to 245 F (–40 to 118 C)
Chiller shut down
immediately
Automatic
Thermistor failure, damaged
cable/wire or wiring error.
T068 None Circuit A Return Gas Thermistor Failure
If return gas sensors are
enabled (RG.EN) and
thermistor is outside range of
–40 to 245 F (–40 to 118 C)
Circuit A shut down Automatic
Thermistor failure, damaged
cable/wire or wiring error.
T069 None Circuit B Return Gas Thermistor Failure
If return gas sensors are
enabled (RG.EN) and
thermistor is outside range of
–40 to 245 F –40 to 118 C)
Circuit B shut down Automatic
Thermistor failure, damaged
cable/wire or wiring error.
T073 Alert
Outside Air Thermistor
Failure
Thermistor outside range of
–40 to 245 F (–40 to 118 C)
Temperature reset
disabled. Chiller runs
under normal control/set
points. When capacity
reaches 0, cooler/pump
heaters are energized.
Automatic
Thermistor failure, damaged
cable/wire or wiring error.
T074 Alert
Space Temperature/Dual Chiller
Thermistor Failure
Thermistor outside range of
–40 to 245 F (–40 to 118 C)
Temperature reset
disabled. Chiller runs
under normal control/set
points.
Automatic
Thermistor failure, damaged
cable/wire or wiring error.
T077 Alert
Circuit A Saturated
Suction Temperature
exceeds Cooler Leaving
Fluid Temperature
Faulty expansion valve,
suction pressure transducer
or leaving fluid thermistor.
Circuit A shutdown after
pumpdown complete.
Automatic
Faulty expansion valve or
suction pressure transducer
or leaving fluid
thermistor.
T078 Alert
Circuit B Saturated
Suction Temperature
exceeds Cooler Leaving
Fluid Temperature
Faulty expansion valve,
suction pressure transducer
or leaving fluid thermistor.
Circuit B shutdown after
pumpdown complete
Automatic
Faulty expansion valve or
suction pressure transducer
or leaving fluid
thermistor.
T079 Alert
Lead/Lag LWT
Thermistor Failure
Thermistor outside range of
–40 to 245 F (–40 to 118 C)
Chiller runs as a stand
alone machine
Automatic
Dual LWT thermistor failure,
damaged cable/wire or
wiring error.
T090 Alert
Circuit A Discharge
Pressure Transducer Failure
Outside of range (0 to
667 psig)
Circuit A shut down Automatic
Transducer failure, poor
connection to MBB, or wiring
damage/error.
T091 Alert
Circuit B Discharge
Pressure Transducer Failure
Outside of range (0 to
667 psig)
Circuit B shut down Automatic
Transducer failure, poor
connection to MBB, or wiring
damage/error.
T092 Alert
Circuit A Suction
Pressure Transducer Failure
Outside of range (0 to 420
psig)
Circuit A shut down Automatic
Transducer failure, poor
connection to MBB, or wiring
damage/error.
T093 Alert
Circuit B Suction
Pressure Transducer
Failure
Outside of range (0 to
420 psig)
Circuit B shut down Automatic
Transducer failure, poor
connection to MBB, or wiring
damage/error.
T094 Alert
Discharge Gas
Thermistor Failure
Discharge thermistor (DTT) is
either open or shorted
Digital compressor shut
down.
Automatic
Thermistor failure, damaged
cable/wire or wiring error.