Carrier 48/50PD05 User Manual
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Table 8 — ComfortLink™ Alarm Codes
ALARM
OR
ALERT
NUMBER
DESCRIPTION
ACTION TAKEN BY
CONTROL
RESET
METHOD
PROBABLE CAUSE
T051
Digital Compressor Control Board Alarm
No action
Automatic
See the DSC’s LEDs for troubleshooting
Compressor A1 Safety Trip
Add Strike for Circuit A
Automatic
Current Sensing turned on (CS.A1 = Enable) and
should be off
Service Test --- Compressor A1 Safety Trip
Add Strike for Circuit A
Automatic
Current Sensing turned on (CS.A1 = Enable) and
should be off
Compressor A1 Current Detected After
Turnoff
Turn off all
compressors
Automatic
Current Sensing turned on (CS.A1 = Enable) and
should be off
Service Test --- Compressor A1 Current
Detected After Turnoff
Turn off all
compressors
Automatic
Current Sensing turned on (CS.A1 = Enable) and
should be off
T064
Circuit A Saturated Condensing Temp
Thermistor Failure
Use OAT to control
Outdoor fans
Automatic
Faulty, shorted, or open thermistor caused by wiring
error or loose connection.
T066
Circuit A Saturated Suction Temperature
Thermistor Failure
No Cooling
Automatic
Suction transducers internally forced inactive
T073
Outdoor Air Temperature Thermistor Failure
No cooling with
economizer
Automatic
Faulty, shorted, or open thermistor caused by wiring
error or loose connection.
T074
Space Temperature Thermistor Failure
No heating or cooling
Automatic
Faulty, shorted, or open thermistor caused by wiring
error or loose connection.
T075
Supply Air Temperature Thermistor Failure
No cooling mode
Automatic
Faulty, shorted, or open thermistor caused by wiring
error or loose connection.
T076
Return Air Thermistor Failure
No differential DB
crossover
Automatic
Faulty, shorted, or open thermistor caused by wiring
error or loose connection.
T077
Space Relative Humidity Sensor Failure
If RH.S = Yes, then no
indoor humidity control
Automatic
Faulty, shorted, or open sensor caused by wiring
error or loose connection.
T092
Circuit A Suction Pressure Transducer
Failure
Shutdown Circuit A
Manual
Faulty transducer, faulty 5---V power supply, or loose
connection
T102
Compressor A1 Current Sensor Failure
If CS.A1 = Enable,
then no T051 current
alarm
Automatic
Current Sensing turned on (CS.A1 = Enable) and
should be off
T110
Circuit A Loss of Charge
Shutdown Circuit A
Manual
Low refrigerant or faulty suction pressure transducer
Service Test --- Circuit A Loss of Charge
Shutdown Circuit A
Manual
Low refrigerant or faulty suction pressure transducer
T126
Circuit A High Discharge Pressure
Shutdown Circuit A
Automatic
An overcharged system, high outdoor ambient
temperature coupled with dirty outdoor coil, plugged
filter drier, or a faulty high---pressure switch.
Service Test --- Circuit A High Discharge
Pressure
Shutdown Circuit A
Automatic
An overcharged system, high outdoor ambient
temperature coupled with dirty outdoor coil, plugged
filter drier, or a faulty high---pressure switch.
T133
Circuit A Low Refrigerant Pressure
Add Strike for Circuit A
Automatic
Low refrigerant charge, dirty filters, evaporator fan
turning backwards, loose or broken fan belt, plugged
filter drier, faulty transducer, excessively cold return
air, or stuck open economizer when the ambient
temperature is low.
Service Test --- Circuit A Low Refrigerant
Pressure
Add Strike for Circuit A
Automatic
Low refrigerant charge, dirty filters, evaporator fan
turning backwards, loose or broken fan belt, plugged
filter drier, faulty transducer, excessively cold return
air, or stuck open economizer when the ambient
temperature is low.
T143
Circuit A Failure To Pressurize
Add Strike for Circuit A
Automatic
Wiring causing reverse rotation or faulty compressor
Service Test --- Circuit A Failure To
Pressurize
Add Strike for Circuit A
Automatic
Wiring causing reverse rotation or faulty compressor
T153
Real Timeclock Hardware Failure
No time and date
schedule operation
Automatic
No time/date configured, software failure, or MBB
failure
A154
Serial EEPROM Hardware Failure
Unit Shutdown
Automatic
Software failure or MBB failure
T155
Serial EEPROM Storage Failure Error
Unit operation errors
Automatic
Software failure or MBB failure
A156
Critical Serial EEPROM Storage Fail Error
Unit Shutdown
Automatic
Software failure or MBB failure
A157
A/D Hardware Failure
Unit Shutdown
Automatic
Software failure or MBB failure
A163
Circuit A Down Due to Failure
Shutdown Circuit A
Manual
Circuit has 3 strikes or has been locked out by
another alarm
Service Test --- Circuit A Down Due to
Failure
Shutdown Circuit A
Manual
Circuit has 1 strike or has been locked out by another
alarm
* See Legend on next page
48/
50P
D