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P6

Mitsubishi Electric Split AC

Severity: Moderate

Source: OnlyErrorCodes.com — Every error code. One place.

Mitsubishi AC P6 Error — Coil Freeze Protection

What Does This Error Mean?

P6 on a Mitsubishi Electric AC means the indoor heat exchanger temperature has dropped to freezing — typically caused by reduced airflow over the coil. The unit pauses to prevent ice damage. Clean the indoor air filter and check the indoor fan — these resolve most P6 events.

Affected Models

  • Mitsubishi Electric MSZ-AP
  • Mitsubishi Electric MSZ-LN
  • Mitsubishi Electric MSZ-EF
  • Mitsubishi Electric MSZ-HR
  • Mitsubishi Electric MSZ-FH

Common Causes

  • Dirty indoor air filter blocking airflow over the evaporator (most common)
  • Failed or slow indoor fan motor
  • Low refrigerant charge causing low evaporator temperature
  • Set point too low (e.g., 16°C) in low-load conditions
  • Frozen evaporator coil from extended low-temperature operation

How to Fix It

  1. Switch off the AC and let it thaw.

    If P6 just triggered, ice may be on the coil. Run only the fan (no cooling) for 30 minutes to melt any ice. Or simply switch off and leave for 1 hour.

  2. Clean the indoor air filter.

    Open the indoor unit panel and remove the air filter. Wash with warm soapy water, rinse, and air-dry. A filter caked with dust is the leading cause of P6 — clean every 2–4 weeks in heavy use.

  3. Check the indoor fan.

    Restart the AC and listen for the indoor fan running steadily. Slow fan speed or unusual noises suggest fan motor issues that reduce airflow and trigger P6.

  4. Adjust the set point.

    Setting the AC to 16°C in mild weather creates very low cooling load — the evaporator runs cold long enough to freeze. Set 22–24°C for normal cooling, only lower for severe heat.

  5. Book service if P6 returns with a clean filter.

    Repeat P6 with a clean filter and good fan operation suggests low refrigerant — service can confirm with pressure measurement. Service cost: USD 150–250 for diagnosis; refrigerant repair USD 200–600.

Frequently Asked Questions

How can I tell if my filter is dirty enough to cause P6?

Hold the filter up to bright light. If light barely passes through, it is clogged. A clean filter looks light grey, transmitting most light. Filters left more than 2 months in heavy use are usually too dirty.

Will P6 damage my Mitsubishi AC?

P6 itself is the protection — the AC stops before damage occurs. But ignoring P6 and forcing operation can cause coil freezing, then thawing, then water leaks. Address P6 promptly to avoid these secondary issues.