Indoor unit shows P3; system may limit capacity or shut down intermittently.

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.

Possible Causes

Outdoor ambient temperature too low for selected mode, Faulty outdoor ambient sensor, Incorrect system configuration

How to Fix / Troubleshooting

Safety first: No internal access is usually required for this code.

Steps:

Check outdoor temperature: Verify that the outdoor temperature is within the operating range for cooling or heating as specified by MrCool.
Mode selection: Avoid running cooling when outdoor temperatures are very low unless the system is rated for low-ambient cooling.

If P3 appears in normal conditions: The outdoor ambient sensor (T4) may be faulty and should be tested and replaced by a technician if needed.

Repair Difficulty

Medium 3/5

Required Part

Outdoor Ambient Temperature Sensor (T4)

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