E6
iComfort Accessory Control Output Fault

Thermostat shows E6 and will not control dehumidification or humidification functions

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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

Shorted dehumidifier/humidifier output terminal, Failed accessory relay on thermostat main board, Miswired accessory to wrong iComfort terminal, Overcurrent from connected accessory

How to Fix / Troubleshooting

Safety first: Turn off power to the HVAC system and any connected humidifier/dehumidifier at the breaker.

  • Step 1 – Inspect accessory wiring: Remove the thermostat and verify that humidifier/dehumidifier wires are connected to the correct iComfort accessory terminals as per the installation manual.
  • Step 2 – Look for shorts: At the accessory device, inspect wiring for bare conductors touching metal or each other. Repair any damaged insulation.
  • Step 3 – Disconnect accessory: Temporarily disconnect the accessory wires at the thermostat. Restore power and see if E6 clears. If it does, the accessory or its wiring is the source of the fault.
  • Step 4 – Check accessory load: Confirm that the connected humidifier/dehumidifier does not exceed the rated current for the thermostat’s accessory output. If it does, an isolation relay kit is required.
  • Step 5 – Replace thermostat board: If E6 persists even with accessory wiring removed, the accessory relay or output driver on the thermostat main board may be damaged and the thermostat should be replaced.
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Repair Difficulty

Medium 3/5

Required Part

iComfort Thermostat Main Board (Accessory Output Circuit)
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