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Carrier Air Conditioner E1 Error Code
Ductless indoor and outdoor units not talking on Carrier air conditioners.
CarrierAll Carrier air conditioner codes
The wall unit has gone quiet on its outdoor unit: it got no reply for 110 seconds four times in a row. Carrier's list of causes is a wiring mistake or a faulty indoor or outdoor board.
Compatible models
High-wall ductless indoor units in Carrier's 40MAQ and 40MHH series, per their service manuals.
Also shown as
The operation lamp blinks twice on units that show the fault that way. Carrier notes the interconnecting wiring is polarity-sensitive and thermostat wire must not be used for it, so a new install is the first suspect.
Difficulty
Start with the safe checks below; a worn part may need replacing.
Not sure you are reading the code right? See how to read Carrier air conditioner codes.
How to fix Carrier E1
Check the outdoor breaker and disconnect
Ductless indoor units are often fed power through the outdoor unit. A tripped outdoor breaker or a pulled disconnect can bring up E1.
Do a long power reset
Carrier's own ductless advice is to turn the unit off and leave the outdoor power off for at least 20 minutes before switching it back on.
Call the installer on a new system
If E1 started right after installation, ask the installer to recheck the connections between the units.
When to call a technician
When power is good at both ends and E1 still returns, a technician needs to measure the signal on the interconnecting wiring and test the boards.
Parts linked to E1
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 E1 code?
High-wall ductless indoor units in Carrier's 40MAQ and 40MHH series, per their service manuals.
Can I fix Carrier E1 myself?
Often. The first steps above are safe checks a homeowner can do. If they don't clear E1, the cause is likely a worn part that needs replacing.
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
- 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
- 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.