All 19 Carrier air conditioner codes
- Solid / 1 / 2Status light showing normal operation
- 16Lost communication with the Infinity control
- 25Model plug missing or wrong
- 31 / 84High-pressure switch tripped or locked out
- 32 / 83Low-pressure or discharge temperature trip
- 45Outdoor control board fault
- 46Brown-out: supply voltage too low
- 47No 230-volt power reaching the outdoor unit
- 53 / 55 / 56Outdoor air or coil sensor fault
- 71 / 72 / 81 / 82Compressor thermal cutout or lockout
- 73 / 74Contactor stuck closed or not closing
- E1Ductless indoor and outdoor units not talking
- ECRefrigerant leak detected
- E3 / F5Ductless fan speed out of range
- E4 / E5 / F1 / F2 / F3Ductless temperature sensor open or shorted
- F0 / P1Ductless overcurrent or voltage protection
- P3Too cold outside to heat
- P5Multi-zone mode conflict
- CL / dFFilter reminder or defrost in progress
About Carrier air conditioner error codes
Carrier is an American heating and cooling company founded by Willis Carrier, the engineer credited with inventing modern air conditioning. Carrier central air conditioners and heat pumps report faults by flashing a status light on the outdoor unit's control board, while its ductless mini-splits show a code on the indoor unit's display.
How to read Carrier air conditioner codes
Carrier's two-stage outdoor units, including the Infinity 24ANB7 air conditioner and the 25HNB6 and 25HNB9 heat pumps, report faults on an amber STATUS light on the outdoor control board. It blinks a two-digit number: short blinks give the first digit and long blinks the second, so three short and two long means code 32. The pattern repeats after a pause of about 2.5 seconds. The board is inside the outdoor unit's electrical box, so a technician usually reads it.
Carrier's high-wall ductless units (40MAQ and 40MHH series) show letter codes such as E1, F0 or P1 on the indoor display, or blink the operation lamp a set number of times. Other Carrier ductless lines and the variable-speed Infinity outdoor units use their own lists, and the same number can mean something different there, so match the code to the manual for your model.
To reset a ducted system, switch off the outdoor disconnect and the furnace or fan coil breaker together for a few minutes. For ductless systems Carrier suggests leaving outdoor power off for at least 20 minutes. Before you book service, note the code and the model number from the rating plate on the outdoor unit.
Of the 19 codes on this page, 4 usually have a simple fix you can do yourself, and 7 usually need a technician. Each guide says which is which, so you don't pay for a service call you don't need, and you don't attempt a repair that isn't safe.
Carrier air conditioner repair guides
- AC Blowing Warm Air? 8 Causes and What You Can Fix Yourself
Warm air from an AC is most often a wrong mode setting, clogged indoor filters, or an outdoor unit that has lost power or stopped.
- AC Freezing Up? Why the Indoor Coil Ices Over and What to Do
An AC that freezes up almost always has too little air moving across the indoor coil, and a clogged filter is the first suspect.
- AC Leaking Water Indoors? 6 Causes and How to Fix Each One
An indoor AC unit that drips is usually dealing with condensate that can't drain away: a clogged drain line, a coil that froze because the filters are dirty, or a unit or drain hose that isn't sloped correctly.
- Heat Pump Not Heating? Settings, Defrost and Fixes to Try
A heat pump that seems to stop heating is often just in its defrost cycle, which Trane says usually lasts 3 to 5 minutes and can send cool air or steam out of the outdoor unit.
- How to Clean Mini-Split Filters: Step-by-Step for Wall Units
Switch the unit off, lift the front panel, slide out the mesh filters, vacuum or wash them in lukewarm water with mild detergent, and let them dry completely in the shade before you put them back.
- How to Reset a Mini-Split AC: Breaker, Button and Remote Fixes
The standard mini-split reset is a power reset: turn the unit off with the remote, switch off its breaker or outdoor disconnect, leave it off for about 20 minutes (Carrier's figure), then restore power and give the compressor 3 minutes to start.
Before you start
- Write down your model number. It's on a sticker, usually inside the door or lid, on the frame, or on the back or side panel. Parts and some code meanings depend on it.
- Try a reset. Unplug the air conditioner or switch off its breaker for 10 minutes. This clears many one-off glitches without tools.
- Clean or replace the air filter first. A dirty filter causes many airflow and freezing codes.
- Never open refrigerant lines or electrical panels. Those are jobs for a licensed HVAC technician.