Mitsubishi Electric mini split error code UF
Compressor over-current (locked compressor).
- TypeProtection
- SystemCompressor / inverter
- Can I fix it?Technician job
What UF means on a Mitsubishi Electric
The compressor drew more current than its limit, usually because it could not turn.
On this platform, UF is a protection: the system stopped or throttled itself to prevent damage; many clear on their own once conditions return to normal.
Common causes
- A seized or failing compressor.
- Liquid refrigerant flooding after sitting cold.
- Low supply voltage.
- A failed inverter.
How to fix it yourself
Do the reset and the visual checks, but the underlying repair needs a technician with a meter and the service manual.
- Reset the system: switch the breaker (or the outdoor disconnect) off, wait a full five minutes so the boards fully discharge, then switch it back on and restart from the remote.
- If you own a multimeter and are comfortable using it, measure the supply voltage at the outdoor unit's L1 and L2 terminals with the unit running. A 230 V system should read roughly 208 to 253 VAC.
- Do not keep retrying after two failed starts.
Switch off power at the breaker before opening either unit. Capacitors in the outdoor unit hold a charge for several minutes after power is cut.
When to call a technician
Technician diagnosis of the compressor and drive.
Which Mitsubishi Electric units show UF
This page applies to Mitsubishi Electric M-Series (MSZ), Mr. Slim (PKA/PCA), Hyper-Heating H2i and MXZ multi-zone units. Mitsubishi Electric's own documentation lists UF as "Compressor over-current (locked compressor)", the same definition used across the Mitsubishi Electric it is built on. If your unit shows a code with a different shape (for example a four-character code, or a plain number), it is from a different table; use the lookup with your exact code.
Where Mitsubishi Electric shows this code
Wall units without a wired controller signal a fault by blinking the operation indicator lamp; the code itself shows on a wired controller (MHK/PAR series) or on the wireless remote after entering its check mode (see your manual). On the outdoor unit, the control board LEDs blink the same code. P codes are indoor-unit faults, E codes are communication faults, F codes are outdoor-unit faults and U codes are outdoor-unit and compressor faults.
Other Mitsubishi Electric codes
Same part of the system as UF:
UF on other brands
The same characters do not always mean the same thing. Check the brand on your unit.
Questions people ask
Can I reset a Mitsubishi Electric UF code myself?
Yes. Turn the system off at the breaker for five minutes, then restart it. If UF comes back, the fault is real and needs the checks above.
Is it safe to keep running a Mitsubishi Electric showing UF?
Not repeatedly. A protection code means the unit stopped itself to prevent damage, and resetting it over and over can turn a cheap repair into a compressor failure. Reset once, check the basics, and stop if it returns.
What will a technician check for UF?
Technician diagnosis of the compressor and drive. Ask for the measurements, not just a parts quote.
Sources
- Mitsubishi Electric M-Series and Mr. Slim service manuals (self-diagnosis tables)
Updated September 2026. Codes and definitions vary by model year. If your manual disagrees with this page, your manual wins. Send a correction.