U4
Mitsubishi Heavy
Mitsubishi Heavy air conditioner error U4
Meaning
Outdoor thermistor short/open
General meaning for the brand's models, unless a model's own manual says otherwise.
Causes and how to check
- the cited manual page, and follow-up questions
No account needed to look up codes.
Guides
- Checking an air conditioner temperature sensor (thermistor)
How to check the room, coil or discharge sensor when the unit reports a sensor error: measure its resistance and compare with the exact model's table.