Keystone Compressor Overload / High Discharge Temperature Protection

Keystone portable air conditioner displays P4 and may shut down unexpectedly.

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.

Possible Causes

Blocked exhaust duct (portable models), dirty condenser, failing condenser fan, high ambient temperature, faulty discharge sensor

Steps:

Check exhaust hose: Ensure the hose is not kinked, crushed, or excessively long. The window kit should be properly installed with no recirculation of hot air.
Clean condenser: Remove dust from the hot coil and fan area.
Verify fan speed: Confirm the hot-side fan runs strongly. Replace the fan motor if weak or intermittent.
Sensor inspection: Locate the discharge line sensor and ensure it is attached firmly. Replace if faulty.

Medium 3/5

Condenser Fan Motor or Discharge Line Sensor

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