Dometic Air Conditioner: “E3”
warning RV air conditioner error codes
What it means
The indoor (return-air) temperature sensor is reading as shorted. As with E2, all heating and cooling are locked out, but manual fan operation can still run.
Most likely causes
- Shorted indoor temperature sensor most likely
- Sensor wiring shorted or pinched against metal common
- Failed control board sensor input less common
Safe checks you can do yourself
- Power-cycle the system at the breaker to rule out a transient fault.
- Confirm fan-only mode still operates, which is consistent with an indoor-sensor fault.
- Visually check for obviously pinched or damaged sensor wiring if accessible; do not attempt internal repairs.
How to reset / clear E3
- Turn the thermostat OFF.
- Remove power at the AC breaker for about a minute, then restore power.
- If E3 returns, the indoor sensor or its wiring requires service.
When to call a technician
If E3 persists, have a qualified technician replace the indoor temperature sensor and verify the control board.
Applies to
Dometic Comfort Control Center 2 (CCC2) thermostat systems · Dometic Single Zone LCD thermostat systems
FAQ
What does Dometic Air Conditioner code "E3" mean?
The indoor (return-air) temperature sensor is reading as shorted. As with E2, all heating and cooling are locked out, but manual fan operation can still run.
How do I reset Dometic Air Conditioner E3?
Turn the thermostat OFF. Remove power at the AC breaker for about a minute, then restore power. If E3 returns, the indoor sensor or its wiring requires service.
What is the most common cause of E3 on a Dometic Air Conditioner?
The most likely cause is shorted indoor temperature sensor.
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Sources
- Comfort Control Center 2 Thermostat User's Guide — Section N, LCD Error Code (Error Code: E3) (Dometic Corporation)
- Single Zone LCD Thermostat User's Guide — LCD Error Code (Error Code: E3) (Dometic (via Prime Time RV component manuals))
Note: E3 = shorted indoor temperature sensor (vs. E2 = open/out-of-range). Confirmed on both CCC2 and Single Zone LCD guides.
● Last verified 2026-06-29 · compiled from manufacturer documentation. Codes can vary by model year — always cross-check your unit’s manual.