E2
Fraser-Johnston
Indoor Coil (Evaporator) Freeze Protection / Low Temperature Fault
Indoor unit shows E2 and stops cooling; fan may still run
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Dirty indoor evaporator coil, Restricted airflow due to clogged return filter, Failed or mispositioned indoor coil temperature sensor (thermistor), Low refrigerant charge causing coil icing
How to Fix / Troubleshooting
Safety: Turn off power at the breaker before removing indoor unit panels.
- Check air filter: Remove and inspect the return air filter in the Fraser‑Johnston air handler or wall cassette. If dirty, replace or wash (if reusable). Run the system after cleaning to see if E2 clears.
- Inspect evaporator coil: Remove the front cover and access panel to view the indoor coil. If it is iced over, leave the system OFF and allow ice to melt completely (place towels or a pan to catch water). Clean the coil with a soft brush and approved coil cleaner.
- Verify blower operation: Ensure the indoor blower motor runs at normal speed. A failing ECM blower motor or blocked blower wheel can reduce airflow and cause freezing.
- Check coil sensor: Locate the evaporator thermistor clipped to the coil tubing. Ensure it is firmly attached and not dangling. If the sensor is cracked, corroded, or reading out of range (check resistance vs. temperature chart), replace it.
- If icing recurs: Low refrigerant or metering device issues may be present. This requires a licensed HVAC technician to check pressures and charge.
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Repair Difficulty
Medium
3/5
Required Part
Indoor Coil Temperature Sensor (Evaporator Thermistor)
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