Rheem Dehumidification Control Not Operating

Thermostat is not controlling a whole-house dehumidifier or overcooling for dehumidification as expected.

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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

Dehumidification feature disabled in settings, Incorrect DHUM wiring, Misconfigured dehumidification mode (overcool vs dedicated), Failed DHUM output

How to Fix / Troubleshooting

Steps:

  • Check dehumidification settings: In the Rheem thermostat menu, verify dehumidification is enabled and the setpoint is below current humidity.
  • Verify wiring: Ensure the DHUM or dehumidifier terminals are wired correctly to the dehumidifier or to the air handler's dehumidification input.
  • Test DHUM output: With a dehumidification call active, measure for control voltage at the DHUM terminals.
  • Confirm equipment capability: Make sure your Rheem system supports dehumidification via thermostat control (some require specific indoor units).
  • If wiring and settings are correct but no operation: The DHUM output driver may be failed; thermostat or board replacement may be needed.
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Repair Difficulty

Medium 3/5

Required Part

Dehumidifier Control Circuit
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