Mitsubishi Electric P6

What does Mitsubishi Electric P6 mean?

The indoor unit's freezing or overheating safeguard has operated, shown as P6 on the wired controller. The control stops the unit when the indoor coil gets too cold in cooling (freezing) or too hot in heating (overheating). It is a protective response, usually triggered by restricted airflow or a refrigerant-side condition rather than a single failed component.

Symptoms

• P6 displayed on the wired controller
• Indoor unit stops during cooling or heating
• Ice on the indoor coil (cooling) or very hot coil (heating)
• Weak airflow from the indoor unit

Common causes

• Dirty or clogged air filter restricting airflow
• Blocked indoor coil or supply/return grilles
• Indoor fan running slowly or not at all
• Refrigerant charge problem

Diagnostic steps

1. 01

   Power down the unit

   Turn the system off and let the coil return to normal temperature.

2. 02

   Clean or replace the filter

   Restore airflow by cleaning or replacing the indoor air filter.

3. 03

   Clear airflow paths

   Check that supply and return grilles and the indoor coil are not blocked.

4. 04

   Confirm the indoor fan runs

   Verify the indoor fan operates at normal speed.

5. 05

   Restart and monitor

   Restore power and watch whether P6 returns once airflow is restored.

When to call a professional

Call a technician if P6 keeps tripping after airflow is restored, since a persistent freezing or overheating safeguard can point to a refrigerant-side problem that needs gauges to diagnose. Checking the charge and the indoor coil's operation requires certification and service tools, so have a qualified professional investigate a repeated P6.