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Table 114 — Alert and Alarm Codes
ALARM OR
ALERT
NUMBER
DESCRIPTION ACTION TAKEN BY CONTROL
RESET
METHOD
PROBABLE CAUSE
A051 Circuit A, Compressor 1 Stuck On Failure Turn off all compressors Manual Welded contact
P051 Circuit A, Compressor 1 Failure Add strike to compressor
Automatic
(max 3)
High pressure switch, compressor
current, wiring error
T051 Circuit A, Compressor 1 Failure Compressor locked off Manual Exceeded 3 strike limit
A052 Circuit A, Compressor 2 Stuck On Failure Turn off all compressors Manual Welded contact
P052 Circuit A, Compressor 2 Failure Add strike to compressor
Automatic
(max 3)
High pressure switch, compressor
current, wiring error
T052 Circuit A, Compressor 2 Failure Compressor locked off Manual Exceeded 3 strike limit
A055 Circuit B, Compressor 1 Stuck On Failure Turn off all compressors Manual Welded contact
P055 Circuit B, Compressor 1 Failure Add strike to compressor
Automatic
(max 3)
High pressure switch, compressor
current, wiring error
T055 Circuit B, Compressor 1 Failure Compressor locked off Manual Exceeded 3 strike limit
A056 Circuit B, Compressor 2 Stuck On Failure Turn off all compressors Manual Welded contact
P056 Circuit B, Compressor 2 Failure Add strike to compressor
Automatic
(max 3)
High pressure switch, compressor
current, wiring error
T056 Circuit B, Compressor 2 Failure Compressor locked off Manual Exceeded 3 strike limit
T064
Circuit A Saturated Condensing Thermistor Failure
(48/50AJ,AK,AW,AY units only)
Use OAT for head pressure control Automatic Faulty thermistor or wiring error
T065
Circuit B Saturated Condensing Thermistor Failure
(48/50AJ,AK,AW,AY units only)
Use OAT for head pressure control Automatic Faulty thermistor or wiring error
T072 Evaporator Discharge Reset Sensor Failure Unit shutdown Automatic Faulty remote input on CEM board
T073 Outside Air Temperature Thermistor Failure Stop use of economizer Automatic Faulty thermistor or wiring error
T074 Space Temperature Thermistor Failure Unit shutdown Automatic Faulty thermistor or wiring error
T075 Return Air Thermistor Failure Continue to run unit Automatic Faulty thermistor or wiring error
T076 Outside Air Relative Humidity Sensor Failure Use OAT changeover control Automatic Faulty sensor or wiring error
T078 Return Air Relative Humidity Sensor Failure Use differential dry bulb changeover Automatic Faulty sensor or wiring error
T082 Space Temperature Offset Sensor Failure Use Space temperature without offset Automatic Faulty sensor or wiring error
T090 Circuit A Discharge Pressure Transducer Failure Stop circuit Automatic Faulty sensor, wiring error
T091 Circuit B Discharge Pressure Transducer Failure Stop circuit Automatic Faulty sensor, wiring error
T092 Circuit A Suction Pressure Transducer Failure Stop circuit Automatic Faulty sensor, wiring error
T093 Circuit B Suction Pressure Transducer Failure Stop circuit Automatic Faulty sensor, wiring error
T110 Circuit A Loss of Charge Stop circuit Manual Low refrigerant charge
T111 Circuit B Loss of Charge Stop circuit Manual Low refrigerant charge
A120 Circuit A Low Saturated Suction Temperature Alarm. Stop circuit Manual
Low refrigerant charge, low airflow,
dirty coil, broken fan belt, TXV
problem
P120 Circuit A Low Saturated Suction Temp-Comp A2 Shutdown Compressor A2 shutdown Automatic
Low refrigerant charge, low airflow,
dirty coil, broken fan belt, TXV
problem
T120 Circuit A Low Saturated Suction Temperature Alert. Stop circuit Automatic
Low refrigerant charge, low airflow,
dirty coil, broken fan belt, TXV
problem
A121
Circuit B Low Saturated Suction Temperature Alarm. Stop circuit Manual
Low refrigerant charge, low airflow,
dirty coil, broken fan belt, TXV
problem
P121 Circuit B Low Saturated Suction Temp-Comp B2 Shutdown Compressor B2 shutdown Automatic
Low refrigerant charge, low airflow,
dirty coil, broken fan belt, TXV
problem
T121 Circuit B Low Saturated Suction Temperature Alert. Stop circuit Automatic
Low refrigerant charge, low airflow,
dirty coil, broken fan belt, TXV
problem
T122 Circuit A High Saturated Suction Temperature Stop circuit Manual TXV problem, high load.
T123 Circuit B High Saturated Suction Temperature Stop circuit Manual TXV problem, high load.
T126 Circuit A High Head Pressure Stop circuit Automatic
Dirty condenser, condenser fan
failure, system overcharged
T127 Circuit B High Head Pressure Stop circuit Automatic
Dirty condenser, condenser fan
failure, system overcharged
A140 Reverse Rotation Detected Stop unit Manual Incorrect compressor wiring
A150 Unit is in Emergency Stop Stop unit Manual External shutdown command
T153 Real Time Clock Hardware Failure Stop unit Manual Control Board failure, check lights
A154 Serial EEPROM Hardware Failure Stop unit Manual Control Board failure, check lights
T155 Serial EEPROM Storage Failure Error Stop unit Manual Control Board failure, check lights
A156 Critical Serial EEPROM Storage Failure Error Stop unit Manual Control Board failure, check lights
A157 A/D Hardware Failure Stop unit Manual Control Board failure, check lights
A171 Staged Gas Control Board Comm Failure Stop gas heat Automatic Control Board failure, check lights
A172 Controls Expansion Module Comm Failure Stop options on CEM Automatic Control Board failure, check lights
A173 ECB1 Board Communication Failure Stop economizer & power exh Automatic Control Board failure, check lights
A174 ECB2 Board Communication Failure Stop unit Automatic Control Board failure, check lights
T177 4-20 MA Demand Limit Failure Stop demand limiting Automatic Input failure, wiring error
T178 4-20 MA Static Pressure Reset/VFD Fail Stop static pressure reset/VFD Automatic Input Failure, wiring error
A200 Linkage Timeout Error - Communication Failure Stop unit Manual Wiring errors, board failures
T210 Building Pressure Transducer Failure Close economizer, stop exhaust Automatic Sensor failure, wiring error
T211 Static Pressure Transducer Failure Stop unit Automatic Sensor failure, wiring error
T220 Indoor Air Quality Sensor Failure Stop IAQ control Automatic Sensor failure, wiring error
T221 Outdoor Air Quality Sensor Failure Use a default value for IAQ Automatic Sensor failure, wiring error
T229 Economizer Minimum Position Override Input Failure
Use software configured
minimum
Automatic Input failure, wiring error