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Error P1 in Air Conditioners


The P1 error in air conditioners is typically related to voltage supply issues affecting the compressor, supplied by the outdoor unit’s control board located in the condenser unit. Below are the recommended steps to identify and resolve this issue:


Initial Actions to Resolve the P1 Error

Restart the Unit:

  • Disconnect the air conditioner for a few minutes.
  • Reconnect it and check if the error disappears.
  • If the error persists, disconnect it again for several minutes before attempting another restart.

Check Voltage and Connections:

  • Use a multimeter to measure the supply voltage to ensure it is within the normal range.
  • Inspect all cable connections, as a loose cable could cause the P1 error.

Diagnosing the Electronic Control Board

If voltage and connections are correct, the issue may lie in the electronic control board of the outdoor condenser unit. Follow these steps:

Check Voltage at the Rectifier Bridge in the PFC Circuit:

  • If the unit is powered by 110 VAC, the voltage after the rectifier bridge should be approximately 150 VDC.
  • If powered by 220 VAC, the voltage should be approximately 300 VDC.
  • If this voltage is not present, check components such as the PTC resistor, power relay, and rectifier bridge.

Inspect the PFC Circuit:

  • Test the continuity between the input and output of the coil or reactor.
  • Check the resistances, diode condition, and capacitors in the circuit.

Examine the IGBT Transistor and PFC Driver:

  • Ensure the IGBT transistor is functioning correctly.
  • If all appears normal, the issue may lie in the PFC circuit’s driver or the IPM circuit.

Interpreting the P1 Error by Brand

For most brands such as Carrier, Libera, Lenox, TCL, Westinghouse, Pioneer, and Mirage, the P1 error is associated with voltage or tension issues affecting the compressor.

However, for other brands like Hitachi, Mitsubishi, Trane, and York, this error may have a different meaning and could be related to abnormal temperature or pressure, typically detected by a sensor.


Temperature Sensor Inspection (Specific Brands)

If the P1 error indicates temperature or pressure issues, follow these steps:

Measure the Resistance of the Disconnected Temperature Sensor:

  • Use a multimeter set to the kilo-ohms scale.
  • The resistance should never be zero or infinite.

Test the Sensor’s Response:

  • When rubbing the sensor with your hand, the resistance should decrease.

Check Sensor Voltage (Connected):

  • Measure the voltage sent by the board to the sensor; it should be close to 2.5 V.

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