AC and heat pump error codes

Invalid model plug or inverter size. The outdoor control does not accept the model plug fitted to this inverter. There is no reset time on this row.

High pressure switch open. The unit steps down capacity for each occurrence and elevates to fault 84 if it happens on the lowest stage. Reset time is 6 minutes, then the unit runs at a reduced stage.

Low pressure trip. The control elevates this to fault 83 after 3 occurrences. Reset time is 6 minutes. The manual's example of the flash pattern is 3 short and 2 long for code 32, and Table 6 calls that low pressure switch open.

Lost inverter communications, the local fault. It occurs after 2 minutes with no communication between the outdoor control and the inverter, and it elevates to fault 48 after 3 consecutive failures within 20 minutes or after 20 minutes of continuous loss.

Brownout. Line voltage at the outdoor unit is low. Reset time is 6 minutes.

Lost inverter communications, elevated from fault 33 after 3 occurrences. The outdoor control and the inverter are not talking.

Outdoor air temperature sensor fault. If this sensor fails, the manual says defrost is initiated from coil temperature and time. There is no reset time on this row.

Coil temperature sensor fault. If this sensor fails, the manual says defrost occurs at each time interval during heating and terminates after 2 minutes.

Outdoor air and coil thermistors out of range. The manual calls this an event. If the thermistors are out of range, defrost occurs at each heating interval and terminates after 2 minutes.

Low pressure lockout for 4 hours, elevated from fault 32 after 3 occurrences. The outdoor unit stops retrying the 6-minute trips.

High pressure lockout for 4 hours, elevated from fault 31 when the stage can no longer be lowered.

Invalid model plug / inverter size: the control does not accept the model plug for this inverter.

High pressure switch open: the unit steps down capacity for each occurrence and elevates to fault 84 if it happens on the lowest stage. Reset time is 6 minutes.

Low pressure trip: the control elevates to fault 83 (low pressure lockout) after 3 occurrences. Reset time is 6 minutes.

Lost inverter communications, the local fault. It is logged after 2 minutes with no communication between the outdoor control (AOC) and the inverter (MOC). It elevates to fault 48 after 3 consecutive failures within 20 minutes, or after 20 minutes of continuous loss of connection. The manual says to refer to fault code 48.

Brownout event: low line voltage reaching the unit. Reset time is 6 minutes.

Lost inverter communications (system malfunction): the outdoor control (AOC) and the inverter (MOC) have stopped communicating. Fault 33 is logged after 2 minutes with no communication and is elevated to 48 after 3 consecutive failures within 20 minutes, or 20 minutes of continuous loss of connection.

Compressor overcurrent fault. The control elevates this to fault 95 after 5 occurrences. Reset time is 6 minutes.

Outdoor air temperature sensor fault.

Coil temperature sensor fault.

Outdoor air temperature and outdoor coil temperature thermistors are out of range. The manual lists this as an event, not a lockout.

Suction pressure sensor fault. The suction pressure transducer reading cannot be trusted. There is no reset time on this row.

DC volts low, speed limiting. Supply voltage is under 197 V, or a loose wire or the inverter is limiting compressor speed. The table does not list a reset time.

Low pressure lockout for 4 hours, elevated from fault 32 after 3 occurrences.

High pressure lockout for 4 hours, elevated from fault 31 when the stage (speed) can no longer be lowered.

Compressor and inverter lockout for 2 hours, elevated from fault 79 after 5 occurrences. The compressor failed to start often enough that the control stopped the retries.

Compressor overcurrent lockout for 2 hours, elevated from fault 49 after 5 occurrences.

Freeze-up protection or heating peak-cut: the indoor heat exchanger got too cold in cooling or too hot in heating.

Indoor fan motor fault: the DC fan is not reaching the speed the control asked for.

Outdoor fan lock: the outdoor fan does not start within 15 to 30 seconds.

Four-way valve abnormality: room temperature and indoor coil temperature stay out of range for the mode.

Signal transmission error between the indoor unit and the outdoor unit.

Serial communication error: the indoor unit is not receiving the serial signal from the outdoor unit. The operation lamp blinks once and the timer lamp blinks once.

Room temperature sensor error: the room-temperature thermistor is open or shorted. The operation lamp blinks 4 times and the timer lamp blinks once.

Indoor fan motor error: fan speed stayed below one-third of the target for more than 56 seconds. The operation lamp blinks 5 times and the timer lamp blinks once.

Inverter error: the outdoor unit received an error from the inverter board. The operation lamp blinks 6 times and the timer lamp blinks 3 times.

4-way valve error: heat-exchanger temperature and room temperature stay too far apart for the mode. The operation lamp blinks 9 times and the timer lamp blinks 9 times.

Low pressure cutout: the low pressure switch tripped 3 times within the same thermostat call, so the compressor and outdoor fan are off.

High side fault: four consecutive compressor protector trips with average run time between trips of more than 1 minute and less than 15 minutes, with the low and high pressure switches closed.

Short cycling: the outdoor unit is cycling on and off too quickly.

Locked rotor: the compressor is not turning properly.

Open circuit. The compressor and outdoor fan have been off for more than 4 hours, and both pressure switches are closed.

Open start circuit. The compressor and outdoor fan are off, and both pressure switches are closed.

Open run circuit. The compressor and outdoor fan are off, and both pressure switches are closed.

No line voltage. The unit may appear to be operating normally, and the compressor protector may be open so the compressor and outdoor fan are off.

Low pilot voltage. The air conditioner or heat pump may appear to be operating normally. The chart's note says the control detects secondary voltage less than 18 VAC.

Outdoor air temperature sensor fault. The integrated control module shows A2. The air conditioner or heat pump may show only this code, with no separate symptom line on this row.

Outdoor coil temperature sensor fault. The chart says the heat pump fails to operate in heating mode, and the display shows A3.

Circulator blower motor is not running when it should be. The air conditioner or heat pump fails to operate, and the display shows b0.

Airflow is lower than demanded. The air conditioner or heat pump operates at reduced performance, or in low stage when high stage was expected. The display shows b9.

Data not yet on the network. The air conditioner or heat pump fails to operate.

Invalid data on the network. The air conditioner or heat pump fails to operate.

System mismatch: the outdoor and indoor units are not an acceptable combination, or the airflow trim settings are set to a prohibited value.

Configuration mismatch. The air conditioner or heat pump fails to operate.

Invalid shared data. The air conditioner or heat pump fails to operate. The chart says the code clears once data is loaded.

Open fuse: the low-voltage fuse on the control is blown.

Board misoperation: the manual lists welded compressor relay contacts as the error condition.

High line voltage: the unit may seem to run normally, but the compressor protector may be open (compressor and outdoor fan off).

Open start-circuit lockout. The open start circuit was detected 4 times, with a 5-minute delay between each detection. The compressor and outdoor fan are off.

Open run-circuit lockout. The open run circuit was detected 4 times, with a 5-minute delay between each detection. The compressor and outdoor fan are off.

Low line voltage: the supply voltage to the outdoor unit is below the specified range.

Compressor protector open. The compressor is off.

Indoor coil or room thermistor fault: the sensor is shorted or open. The left lamp blinks twice, then pauses 2.5 seconds.

Indoor fan motor fault: the fan is not reporting rotation. The left lamp blinks 3 times, then pauses 2.5 seconds.

Outdoor power system fault: the compressor stopped three times for overcurrent or start-up failure within a minute of starting. The left lamp blinks 5 times.

Outdoor control fault: the inverter board or outdoor control board cannot read its memory. The left lamp blinks 7 times.

Miswiring or serial signal: the outdoor unit's serial signal was missing for 6 minutes. The left lamp blinks 0.5 second on and 0.5 second off, with no counted pause.