TP-Link Kasa Miswired Heat Call or Incorrect System Type

Thermostat causes furnace to run fan only with no heat when calling for heat

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.

Possible Causes

W and G wires swapped, Thermostat configured for heat pump instead of conventional, Incorrect jumper settings on furnace board, Misassigned terminals in app

How to Fix / Troubleshooting

Safety: Turn off power to furnace before adjusting wiring.

Check wiring: Verify that the W wire is on W and G wire is on G at both thermostat and furnace board.
System type: In the Kasa app, ensure the system is set to conventional furnace if you do not have a heat pump.
Re-run setup: Use the Kasa installation wizard to auto-detect wiring where supported.
Test operation: After corrections, test Heat mode. If fan only still runs, have a technician inspect furnace control board configuration.

Repair Difficulty

Medium 3/5

Required Part

Thermostat Wiring / Furnace Control Board Configuration

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