Coleman-Mach Air Conditioner: “E2”
warning RV air conditioner error codes
What it means
The indoor (room) temperature sensor reads as an open circuit or its value is outside the valid range. Because the thermostat can't trust the room temperature, it locks out heating and cooling, but the fan can still be run manually.
Most likely causes
- Open or broken indoor/room temperature sensor or its wiring most likely
- Disconnected or corroded sensor connector at the thermostat/board common
- Failed indoor temperature sensor common
- Failed thermostat input circuit less common
Safe checks you can do yourself
- If a remote room sensor is used, check that its plug is fully seated and the wire is undamaged.
- Power-cycle the system to clear a transient reading.
- Inspect the sensor wiring for breaks, pinch points, or corrosion.
- Confirm the correct remote-sensor option is configured if your model uses one.
How to reset / clear E2
- Turn OFF the A/C breaker, wait ~60 seconds, then restore power.
- If the code clears and stays clear, the fault was transient.
- If it returns, the indoor sensor or its wiring likely needs service.
When to call a technician
E2 stays after reseating/inspecting the room-sensor wiring and a power cycle, or the sensor needs replacement.
Applies to
Coleman-Mach single-zone LCD wall thermostat · Coleman-Mach rooftop A/C systems using a remote/indoor room temperature sensor
FAQ
What does Coleman-Mach Air Conditioner code "E2" mean?
The indoor (room) temperature sensor reads as an open circuit or its value is outside the valid range. Because the thermostat can't trust the room temperature, it locks out heating and cooling, but the fan can still be run manually.
How do I reset Coleman-Mach Air Conditioner E2?
Turn OFF the A/C breaker, wait ~60 seconds, then restore power. If the code clears and stays clear, the fault was transient. If it returns, the indoor sensor or its wiring likely needs service.
What is the most common cause of E2 on a Coleman-Mach Air Conditioner?
The most likely cause is open or broken indoor/room temperature sensor or its wiring.
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Sources
- Coleman air conditioner error codes (E2 indoor temperature sensor open/out of range) — Coleman-Mach Single Zone LCD thermostat code list (E2) (Twintech Heating and Cooling)
- Coleman air conditioner codes — Coleman-Mach thermostat E2 indoor sensor fault (KDM Gas)
Note: Original-English compilation of the Coleman-Mach single-zone LCD code list as mirrored by RV HVAC references; the manufacturer PDF code table could not be opened directly. Appears only on LCD-display single-zone thermostats, not on push-button or knob models.
● Last verified 2026-06-29 · compiled from manufacturer documentation. Codes can vary by model year — always cross-check your unit’s manual.