P4
Westinghouse Compressor Discharge Temperature Protection

Unit displays P4 and may stop heating or cooling; often related to compressor discharge temperature.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Blocked condenser coil, low refrigerant charge, non-condensable gases in system, failed discharge temperature sensor, compressor mechanical issue

How to Fix / Troubleshooting

Safety: Turn off power before opening the outdoor unit. Components may be hot.

User-level checks:

  • Clean condenser coil: Remove debris and wash the coil gently with water, avoiding the control box.
  • Check outdoor fan: Ensure the fan runs properly and airflow is not obstructed.
  • Allow cool-down: Let the unit cool for 30 minutes, then restart. If P4 returns, a deeper issue exists.

Professional service: A technician should check the discharge temperature sensor, refrigerant charge, and compressor operation, and replace the sensor or repair the refrigerant circuit as needed.

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Repair Difficulty

Professional Required 5/5

Required Part

Discharge Temperature Sensor
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