E2
Aprilaire
Supply Air Temperature Sensor Fault
Aprilaire whole-home dehumidifier displays E2 and will not 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
Failed supply air thermistor, Sensor knocked loose from discharge area, Damaged sensor harness, Corroded or loose connector at control board
How to Fix / Troubleshooting
Safety first: Turn off power to the dehumidifier before opening any panels.
- Locate supply sensor: Find the supply air temperature sensor near the discharge outlet or on the coil outlet tube, connected to the control board via a small harness.
- Check mounting: Ensure the sensor is properly clipped or strapped in place and not hanging loose in the cabinet.
- Inspect harness: Follow the harness back to the board, checking for abrasions or pinched sections. Reseat the connector on the board.
- Measure resistance: With the sensor unplugged, measure resistance and compare to the thermistor chart. Replace if out of spec or open.
- Replace sensor: Install a new Aprilaire supply air temperature sensor if needed, then restore power and verify the E2 code clears.
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Repair Difficulty
Medium
3/5
Required Part
Aprilaire Supply Air Temperature Sensor
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