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Carrier · Air conditioner

45 Outdoor control board failure

High severity Carrier 2-stage 24ANB/25HNB

What the control is telling you

Amber STATUS light flashes 45: the outdoor control has detected an internal fault.

Applies to: Carrier 24ANB1/24ANB7 two-stage AC

Likely causes

  • Failed outdoor control board

Test and repair steps

  1. Cycle 24 V power once to confirm the code returns.
  2. If it repeats, replace the outdoor board and move the model plug over (two-stage).

Models that show this code

8 models in Carrier 2-stage 24ANB/25HNB

24ANB12424ANB13624ANB14824ANB16024ANB72424ANB73624ANB74824ANB760

Other codes on the same units

  • 16 Lost communication with user interface
  • 25 Invalid model plug / inverter size
  • 31 High pressure switch open
  • 32 Low pressure trip
  • 46 Brownout
  • 47 No 230 V at unit
  • 53 Outdoor air temperature sensor fault
  • 55 Outdoor coil temperature sensor fault

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Source: Carrier Residential AC & HP Application Guideline and Service Manual 24-25-9SM (text export), Table 18 Troubleshooting. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.