F5
Frigidaire Limit Circuit Open / Continuous Fan Mode

Furnace flashes F5; blower runs continuously, no 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

Open high limit switch, Open rollout switch, Miswired fan control, Faulty control board

How to Fix / Troubleshooting

Safety: Turn off power before accessing safety switches.

  • 1. Check filter and airflow: Replace dirty filters and open all vents to reduce overheating.
  • 2. Inspect safety switches: Locate high limit and rollout switches. Ensure wiring is intact and connectors are tight.
  • 3. Reset manual rollout (if tripped): Press the reset button on any rollout switch that has one, after confirming there is no visible flame rollout or vent blockage.
  • 4. Thermostat fan setting: Confirm the thermostat fan is set to AUTO, not ON, which can cause continuous blower operation.
  • 5. Professional service: If F5 persists, a technician should test each safety switch and the control board fan relay.
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Repair Difficulty

Medium 3/5

Required Part

High Limit Switch
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