Carrier 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 display, four-character codes (newer units)
What PC 43 means on a Carrier
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 Carrier units show PC 43
This page applies to Carrier Comfort 38MHRB / 40MHHQ, Comfort 38MGR / 40MGQ, Performance 40MAQ / 38MAQ, Infinity 40MPHA / 38MPRA and Carrier multi-zone units on the indoor display, four-character codes (newer units). Carrier'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 Carrier shows this code
indoor display, four-character codes (newer units): The display shows a two-letter prefix and a two-character suffix, either together (EH60) or alternating (EH, then 60). Write both parts down; the suffix is what identifies the 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 Carrier 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 Carrier 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 Carrier 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
- Carrier 38MHRB Single Zone Ductless Service Manual SG-38MHRB-01 (Diagnosis and Solution section)
- Carrier 40MAQ / 38MAQ High-Wall Ductless Service Manual 40MAQ-01SM (Diagnosis and Solution section)
- Carrier 40MPHA / 38MPRA Infinity High Wall Ductless Service Manual (error code table)
Updated September 2026. Codes and definitions vary by model year. If your manual disagrees with this page, your manual wins. Send a correction.