Coleman-Mach Air Conditioner: “E5”
warning RV air conditioner error codes
What it means
The evaporator freeze sensor is open or reading out of range. Because the thermostat can no longer protect the evaporator coil from icing, it locks out the air-conditioning (compressor) mode. Furnace, electric heat strip, heat pump, and fan modes can still run, and the display shows the last temperature set-point.
Most likely causes
- Freeze sensor not properly seated in the evaporator coil, or its lead disconnected/open most likely
- Damaged, pinched, or corroded freeze-sensor wiring/connector common
- Failed (out-of-range) freeze sensor common
- Wrong/incompatible freeze sensor for the thermostat less common
Safe checks you can do yourself
- Verify the freeze-sensor probe is pushed firmly into the evaporator fins and its connector is seated.
- Inspect the freeze-sensor wiring for breaks, pinch points, or corrosion.
- Power-cycle the system to confirm the fault is persistent.
- In the meantime use furnace/fan if needed (these remain available).
How to reset / clear E5
- Turn OFF the A/C breaker, wait ~60 seconds, then restore power.
- If E5 clears and stays clear, it was transient.
- If it returns, reseat or replace the freeze sensor (qualified service).
When to call a technician
E5 persists after reseating/inspecting the freeze sensor and a power cycle, or the sensor needs replacement and A/C must be restored.
Applies to
Coleman-Mach single-zone LCD wall thermostat · Coleman-Mach rooftop A/C systems with an evaporator freeze sensor
FAQ
What does Coleman-Mach Air Conditioner code "E5" mean?
The evaporator freeze sensor is open or reading out of range. Because the thermostat can no longer protect the evaporator coil from icing, it locks out the air-conditioning (compressor) mode. Furnace, electric heat strip, heat pump, and fan modes can still run, and the display shows the last temperature set-point.
How do I reset Coleman-Mach Air Conditioner E5?
Turn OFF the A/C breaker, wait ~60 seconds, then restore power. If E5 clears and stays clear, it was transient. If it returns, reseat or replace the freeze sensor (qualified service).
What is the most common cause of E5 on a Coleman-Mach Air Conditioner?
The most likely cause is freeze sensor not properly seated in the evaporator coil, or its lead disconnected/open.
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Sources
- E5 code freeze sensor range (Coleman-Mach / Dometic freeze-sensor fault) — Coleman-Mach thermostat E5 freeze-sensor open/out-of-range (JustAnswer)
- Coleman air conditioner error codes (E5 freeze sensor, A/C lockout) — Coleman-Mach Single Zone LCD thermostat code list (E5) (Twintech Heating and Cooling)
Note: Original-English compilation mirroring the Coleman-Mach single-zone LCD code list and corroborating RV service Q&A; manufacturer PDF table not directly openable. LCD-display single-zone thermostats only. A genuinely frozen coil (restricted airflow) can also cause A/C lockout without a sensor fault — clean the return-air filter first.
● Last verified 2026-06-29 · compiled from manufacturer documentation. Codes can vary by model year — always cross-check your unit’s manual.