Geo
Dehumidification Control Not Operating
Thermostat fails to dehumidify using the connected whole‑home dehumidifier or AC overcool feature.
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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
Dehumidifier not wired to correct Geo terminals, Dehumidification feature disabled in settings, Incorrect minimum temperature or overcool limit, Failed dehumidification output driver
How to Fix / Troubleshooting
Safety first: Turn off power to the HVAC system and dehumidifier at the breaker before working on wiring.
- Step 1 – Confirm dehumidification method: Determine whether dehumidification is via a standalone dehumidifier or via AC overcooling.
- Step 2 – Verify wiring: For standalone units, ensure control wires are connected to the correct Geo AUX/DEHUM terminals and to the dehumidifier control input.
- Step 3 – Enable feature in settings: In the thermostat humidity settings, enable Dehumidification and set the desired humidity setpoint and any overcool limits.
- Step 4 – Test operation: Lower the humidity setpoint below current humidity and observe if the dehumidifier or AC engages after any built‑in delay.
- Step 5 – Replace thermostat or use relay: If wiring and settings are correct but the output never energizes, the dehumidification driver may be failed. Use an isolation relay or replace the thermostat head unit.
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Repair Difficulty
Hard
4/5
Required Part
Dehumidification Control Output / AUX Circuit
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