Mitsubishi Heat Pump Error Code P8: How to Fix It

Q: Why does my Mitsubishi heat pump keep showing P8 error?

Recurring P8 errors usually indicate a faulty defrost sensor, failing defrost control board, low refrigerant levels, or chronic airflow restrictions. Professional diagnosis is needed to identify the root cause.

Q: Can I run my heat pump with P8 error code?

You should not continue running the heat pump with a P8 error as it indicates the defrost cycle isn't working properly. This can lead to ice buildup that damages the compressor and reduces efficiency.

Q: How often should defrost cycle run on Mitsubishi heat pump?

The defrost cycle typically runs every 30-90 minutes when outdoor temperatures are below 40°F and humidity is high. Each defrost cycle usually lasts 2-15 minutes depending on ice accumulation.

Q: What causes defrost problems in Mitsubishi heat pumps?

Common causes include dirty air filters, blocked outdoor coils, faulty defrost sensors, failed defrost control boards, low refrigerant levels, or poor airflow around the outdoor unit.

Abstract

Error code P8 on your Mitsubishi heat pump indicates the outdoor coil temperature is abnormal and the defrost cycle isn't completing properly. This happens when ice builds up on the outdoor unit and the system can't effectively remove it, reducing heating efficiency and potentially damaging the compressor.