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Carrier Air Conditioner 45 Error Code
Outdoor control board fault on Carrier air conditioners.
CarrierAll Carrier air conditioner codes
The outdoor control board has failed its own check. Carrier's fix for code 45 is a new board.
Compatible models
Outdoor control boards on Carrier's Infinity two-stage 24ANB7 air conditioners and 25HNB6/25HNB9 heat pumps.
Also shown as
No other codes are listed for this fault.
Difficulty
Try the basic checks, but the usual fix is a technician's job.
Not sure you are reading the code right? See how to read Carrier air conditioner codes.
How to fix Carrier 45
Try one full power cycle
Kill power at the outdoor disconnect and the indoor unit's breaker for about five minutes, then restore it. If the code comes straight back, the board needs replacing.
Note any storm or outage
If lightning or a utility outage came just before the code, mention it when you book service.
When to call a technician
A code 45 that survives a power cycle needs a technician to replace the board and fit the model plug from the old one.
Parts linked to 45
These are the parts most often behind this code. Tap one to see what it does and the signs it is failing.
Order parts by your full model number so they fit.
Frequently asked questions
Which Carrier models show the 45 code?
Outdoor control boards on Carrier's Infinity two-stage 24ANB7 air conditioners and 25HNB6/25HNB9 heat pumps.
Can I fix Carrier 45 myself?
Only the basic checks. You can safely try the steps above, but 45 usually points to a part or fault that needs a technician.
Other 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
- 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
Last reviewed 2026-10-22. Codes and steps can vary by model; check your owner's manual.