E9
Bryant
Dehumidifier Communication or Control Fault
Thermostat shows E9 and dehumidification or whole-home dehumidifier control is disabled.
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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
Disconnected or miswired Bryant whole-home dehumidifier control wiring, Incorrect dehumidifier configuration in thermostat, Failed dehumidifier control board, Low-voltage fuse blown on indoor unit due to wiring short
How to Fix / Troubleshooting
Safety first: Turn off power to the indoor unit and dehumidifier at the breakers. Verify power is off before touching wiring.
Steps to troubleshoot:
- 1. Confirm configuration: In the thermostat installer menu, ensure dehumidification is only enabled if a compatible Bryant dehumidifier or dehumidification mode is installed. Disable if not present.
- 2. Inspect wiring: At the indoor unit and dehumidifier, verify that the control wires (DH, R, C or communicating terminals) are correctly connected and not shorted. Repair any damaged insulation.
- 3. Check low-voltage fuse: On the Bryant indoor control board, inspect the low-voltage fuse (typically 3–5A). Replace if blown, but only after correcting any wiring shorts that caused it.
- 4. Test dehumidifier: Restore power and command dehumidification from the thermostat. If the dehumidifier does not start and E9 remains, the dehumidifier control board may be defective.
- 5. Professional help: Have a technician test the dehumidifier and indoor control board if E9 persists with correct wiring and configuration.
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Repair Difficulty
Hard
4/5
Required Part
Bryant Whole-Home Dehumidifier Control Board
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