E16
Rheem
Defrost Control Communication Fault
Thermostat shows E16 and may indicate 'Defrost control error' on heat pump systems.
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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 defrost control board in outdoor unit, Communication error between thermostat and defrost board, Sensor fault on outdoor coil temperature sensor, Miswired defrost sensor harness
How to Fix / Troubleshooting
Safety first: Turn off power to the outdoor unit at the disconnect before opening panels.
Steps:
- Inspect defrost board: Locate the Rheem defrost control board in the outdoor unit. Check for status LEDs and compare blink codes to the service label.
- Check coil sensor: Verify the outdoor coil temperature sensor is properly clipped to the coil and its wiring harness is intact and fully seated on the board.
- Look for corrosion: Inspect connectors and the board for corrosion or insect damage.
- Reset power: Turn power off for several minutes, then restore and observe if E16 clears.
- If E16 persists and board shows error: The defrost board or coil sensor may need replacement. This should be performed by a qualified technician.
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Repair Difficulty
Professional Required
5/5
Required Part
Defrost Control Board
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