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Mitsubishi Electric Air Conditioner U2 Error Code

Discharge temperature too high or low refrigerant. Here is what it means and how to clear it, easiest fix first.

U2
May need a pro

The refrigerant leaving the compressor is running abnormally hot. Mitsubishi Electric links this to a protection device tripping or the system being short of refrigerant.

U2 meanings can vary slightly by outdoor unit series; check your manual.

Safety first: unplug the air conditioner (or switch off its breaker) before touching filters, hoses or panels. If you smell burning or gas, or see water near the outlet, stop and call a professional.

How to fix Mitsubishi Electric U2

  1. Clear the outdoor unit

    Switch off the breaker. Move anything stored next to the outdoor unit and gently brush leaves and dust off the coil with a soft brush, without bending the fins. Poor airflow won't explain every U2, but it is the one cause you can rule out yourself.

  2. Reset the power at the breaker

    Switch off the breaker that feeds the air conditioner (some systems have separate breakers for the indoor and outdoor units, so switch off both). Wait about five minutes, switch the power back on and restart the unit to see if the code clears.

  3. Stop if the code comes straight back

    If U2 reappears after the reset, switch the system off and leave it off rather than restarting it again and again. Repeated restarts against a protection fault can strain the compressor and other outdoor parts.

When to call a technician

Low refrigerant means a leak that a licensed technician must find and repair. Don't open the refrigerant lines or add refrigerant yourself.

Parts that commonly cause U2

Order parts by your exact model number so they fit.

Other Mitsubishi Electric air conditioner codes

Frequently asked questions

What does U2 mean on a Mitsubishi Electric air conditioner?

The refrigerant leaving the compressor is running abnormally hot. Mitsubishi Electric links this to a protection device tripping or the system being short of refrigerant.

Can I fix Mitsubishi Electric U2 myself?

Only the basic checks. You can safely try the steps above, but U2 usually points to a part or fault that needs a technician.

What if U2 keeps coming back?

A code that returns after a reset and the checks above usually means a part is wearing out. Note when U2 appears (which cycle, how often) and have your model number ready; it helps a technician bring the right part on the first visit.

Last reviewed 2026-10-19. Codes and steps can vary by model; check your owner's manual.

References