Carrier mini split error code PC 03
Pressure protection (high or low pressure switch). Also shown as PC03.
- TypeProtection
- SystemRefrigerant circuit
- Can I fix it?Homeowner checks, then maybe a tech
- Applies toindoor display, four-character codes (newer units)
What PC 03 means on a Carrier
A pressure switch in the outdoor unit opened: either head pressure is too high or suction pressure is too low. The compressor stops.
On this platform, PC 03 is a protection: the system stopped or throttled itself to prevent damage; many clear on their own once conditions return to normal.
Common causes
- High side: blocked outdoor coil, failed outdoor fan, or an overcharge.
- Low side: low charge, closed service valve, restricted line set, or a frozen indoor coil.
- A failed pressure switch.
How to fix it yourself
Work through the checks below first; they resolve most cases. If they do not, the repair itself may need a technician.
- Look at the outdoor unit: clear leaves, cottonwood fluff, snow or ice from the coil and make sure the fan can spin freely and nothing is stacked against the cabinet.
- Confirm both service valves are fully open.
- Pull the front panel and check the filters and the indoor coil. Dirty filters and a matted coil restrict airflow, and airflow problems trigger a surprising number of protection codes.
- If the indoor coil is iced, run Fan-only until it thaws.
- Anything inside the refrigerant circuit (sensors are fine, but valves, compressors and leaks are not) needs EPA-certified refrigerant handling. That is a technician job.
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
A technician needs gauges on the system to tell which side tripped and why.
Which Carrier units show PC 03
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 03 as "Pressure protection (high or low pressure switch)", 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 03:
PC 03 on other brands
The same characters do not always mean the same thing. Check the brand on your unit.
- Pioneer PC 03 Pressure protection (high or low pressure switch)
Questions people ask
Can I reset a Carrier PC 03 code myself?
Yes. Turn the system off at the breaker for five minutes, then restart it. If PC 03 comes back, the fault is real and needs the checks above.
Is it safe to keep running a Carrier showing PC 03?
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.
Do I need a technician for Carrier PC 03?
Work through the checks below first; they resolve most cases. If they do not, the repair itself may need a technician. A technician needs gauges on the system to tell which side tripped and why.
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.