Mitsubishi error code P6 means the compressor temperature exceeded the inverter’s safety limit or the discharge thermistor detected abnormal heat. It’s usually caused by low refrigerant charge (35 %), blocked condenser airflow (30 %), or defective thermistor (20 %). The inverter halts compressor operation instantly to prevent winding burn-out. Average repair cost: $400 – $900 ; compressor replacement can reach $1 800 – $2 300. Fixair technicians perform same-day thermal diagnostics and pressure balance checks to restore safe operation.
Quick Answer — Mitsubishi Error Code P6
Error code P6 means the compressor’s discharge temperature rose beyond safe limits or the thermistor feedback became abnormal.
Common causes: low refrigerant (35 %), dirty or blocked condenser (30 %), faulty thermistor (20 %), and inverter overload (10 %).
Shut the system down immediately to avoid compressor damage.
Check for dirty coils, insufficient refrigerant, or failing fans before resetting.
Average repair cost: $400 – $900; major component replacement $1 800 – $2 300.
Fixair’s thermal specialists resolve most P6 faults within one day.
What P6 Means
When discharge temperature exceeds ≈ 240 °F (115 °C), the outdoor controller shuts the compressor off to prevent burnout.
The thermistor on the discharge line sends a high-temperature signal to the inverter board, triggering code P6.
Ignoring this fault can lead to compressor failure and oil carbonization.
Main Causes of P6
- Low Refrigerant Charge (≈ 35 %) — Insufficient refrigerant reduces cooling of the compressor.
- Blocked Condenser Coil (≈ 30 %) — Restricted airflow traps heat and raises pressure.
- Faulty Discharge Thermistor (≈ 20 %) — Sensor drift reports incorrect temperatures.
- Fan Failure or Motor Overload (≈ 10 %) — Poor heat rejection causes rapid overheat.
- Inverter Overcurrent (< 5 %) — Excessive load during startup spikes temperature.
Immediate Safety Steps
- Turn off power to the system.
- Inspect condenser coils and fans for dust or debris.
- Allow unit to cool for at least 15 minutes.
- Verify refrigerant pressure after cool-down.
- Do not bypass the thermistor or restart until temperature is stable.
- Contact Fixair for pressure testing and sensor evaluation.
Repair Costs and Timeframes (2025)
- Condenser cleaning — $400 – $600 (1–2 h)
- Thermistor replacement — $500 – $700 (2 h)
- Refrigerant recharge — $600 – $900 (2–3 h)
- Compressor replacement — $1 800 – $2 300 (4–6 h)
- Fixair technicians complete temperature and pressure tests same day.
Prevention Tips
- Clean condenser coils every 3 months in summer.
- Check fan rotation and amp draw during each service.
- Monitor discharge temperature via thermistor data log.
- Schedule Fixair maintenance to verify refrigerant charge and sensor accuracy.
- Regular maintenance prevents ≈ 85 % of P6 faults.
Frequently Asked Questions
Is error P6 dangerous?
Yes. It indicates compressor overheating that can lead to failure if ignored.
Can I reset it myself?
Only after checking airflow and refrigerant levels are normal. Otherwise call a technician.
How much does it cost to repair?
$400 – $900 for sensor or cooling issues; $1 800 – $2 300 if compressor is damaged.
How long does it take?
1 – 3 hours for minor repairs; 4 – 6 hours for compressor replacement.
Will it come back?
Not if pressures, temperature, and airflow are kept within manufacturer specifications.
Summary
Error code P6 means the compressor is overheating or the thermistor signal is abnormal. It’s a critical protection that prevents motor burnout.
Turn off power and check refrigerant and airflow before restart. Most repairs cost under $900 and are completed within a day.
