Ideal Stuck Fan Relay / Fan Control Fault

Blower fan runs continuously even when thermostat is not calling for heat

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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

Stuck fan relay on Ideal control board, thermostat fan set to ON instead of AUTO, shorted G (fan) wire to control board

How to Fix / Troubleshooting

Safety: Turn off power before accessing the control compartment.

Steps:

  • Thermostat setting: Check that the fan mode on the thermostat is set to AUTO, not ON.
  • Reset furnace: Turn off power for 2–3 minutes, then restore. If the fan stops and then starts again without a heat call, the relay may be stuck.
  • Inspect G wire: With power off, check the green (G) wire at the thermostat and control board for shorts to other terminals or metal parts.
  • Board replacement: If the fan relay on the Ideal control board is welded closed, the board will need professional replacement.
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Repair Difficulty

Medium 3/5

Required Part

Main Control Board
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