MRCOOL mini split error code PC 43
Compressor missing phase (lack of phase) protection. Also shown as PC43.
- TypeProtection
- SystemCompressor / inverter
- Can I fix it?Technician job
- Applies toindoor unit display (four-character codes)
What PC 43 means on a MRCOOL
The drive detected that one of the three compressor phases is open. Either a compressor lead is off, a winding is open, or the drive output has failed.
On this platform, PC 43 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 loose or burned compressor terminal.
- An open compressor winding.
- A failed inverter output stage.
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.
- With power off, check the compressor terminal cover for loose or scorched spade connectors.
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 job: winding resistance and drive output checks.
Which MRCOOL units show PC 43
This page applies to MRCOOL DIY 2nd/3rd Gen, DIY 4th Gen, DIY Multi-Zone, Advantage, Olympus and Easy Pro units on the indoor unit display (four-character codes). MRCOOL's own documentation lists PC 43 as "Compressor missing phase (lack of phase) protection", the same definition used across the Midea platform (four-character codes) 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 MRCOOL shows this code
The indoor display shows the code in place of the temperature. On DIY 4th Gen units a four-character code alternates between its two halves (EL, then 0C); write down both. The MRCOOL app also reports the current fault.
EH and EL are indoor-side faults, EC is an outdoor-side fault, and PC is an outdoor protection: the unit stopped itself to prevent damage.
Other MRCOOL codes
Same part of the system as PC 43:
PC 43 on other brands
The same characters do not always mean the same thing. Check the brand on your unit.
- Pioneer PC 43 Compressor missing phase (lack of phase) protection
Questions people ask
Can I reset a MRCOOL PC 43 code myself?
Yes. Turn the system off at the breaker for five minutes, then restart it. If PC 43 comes back, the fault is real and needs the checks above.
Is it safe to keep running a MRCOOL showing PC 43?
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 PC 43?
Technician job: winding resistance and drive output checks. Ask for the measurements, not just a parts quote.
Sources
- MRCOOL DIY 3rd Gen and 4th Gen installation manuals (error code tables)
- Midea residential split service manual
Updated September 2026. Codes and definitions vary by model year. If your manual disagrees with this page, your manual wins. Send a correction.