Carrier RAC and Heat Pumps AC Error Codes
*16*
Communication with User Interface lost. Check wiring to User Interface, indoor and outdoor units
Invalid Model Plug
*25*
Control does not detect a model plug or detects an invalid model plug. Unit will not operate without correct model plug.
High Pressure Switch or Discharge Temp Switch Open
*31*
High pressure switch trip. Check refrigerant charge, outdoor fan operation and coils for airflow restrictions.
Low Pressure Switch Open
*32*
Low – pressure switch trip. Check refrigerant charge and indoor air flow.
Control Fault
*45*
Outdoor unit control board has failed. Control board needs to be replaced.
Brown Out (230 v)
*46*
Line voltage < 187v for at least 4 seconds. Compressor and fan operation not allowed until voltage>190v. Verify line voltage.
No 230v at Unit
*47*
There is no 230v at the contactor when indoor unit is powered and cooling/ heating demand exists. Verify the disconnect is closed and 230v wiring is connected to the unit.
Outdoor Air Temp Sensor Fault
*53*
Outdoor air sensor not reading or out of range. Ohm out sensor and check wiring.
Outdoor Coil Sensor Fault
*55*
Coil sensor not reading or out of range. Ohm out sensor and check wiring.
Thermistors out of range
*56*
Improper relationship between coil sensor and outdoor air sensor. Ohm out sensors and check wiring.
Low Stage Thermal Cutout
*71*
Compressor operation detected then disappears while low stage demand exists. Possible causes are internal compressor overload trip or start relay and capacitor held in circuit too long (if installed).
High Stage Thermal Cutout
*72*
Compressor operation detected then disappears while high stage demand exists. Possible causes are internal compressor overload trip or start relay and capacitor held in circuit too long (if installed).
Contactor Shorted
*73*
Compressor voltage sensed when no demand for compressor operation exists. Contactor may be stuck closed or there is a wiring error.
No 230V at Compressor
*74*
Compressor voltage not sensed when compressor should be starting. Contactor may be stuck open or there is a wiring error.
Low Stage Thermal Lockout
*81*
Thermal cutout occurs in three consecutive low/high stage cycles. Low stage locked out for 4 hours or until 24v power recycled.
High Stage Thermal Lockout
*82*
Thermal cutout occurs in three consecutive high/low stage cycles. High stage locked out for 4 hours or until 24v power recycled.
Low – Pressure Lockout
*83*
Low pressure switch trip has occurred during 3 consecutive cycles. Unit operation locked out for 4 hours or until 24v power recycled.
High – Pressure Lockout
*84*
High pressure switch trip has occurred during 3 consecutive cycles. Unit operation locked out for 4 hours or until 24v power recycled.
