F6
Frigidaire
Low Flame / Underfire Condition
Furnace flashes F6; the unit may short-cycle or not complete the heat cycle.
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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
Low inlet gas pressure, partially closed gas shutoff valve, dirty burner orifices, incorrect gas orifice size.
How to Fix / Troubleshooting
Safety: Gas pressure and combustion adjustments must be performed by a licensed technician.
- 1. Verify gas valve position: Ensure the manual gas shutoff valve handle is parallel to the pipe (fully open).
- 2. Check other gas appliances: If other gas appliances are weak or not working, contact your gas utility.
- 3. Visual flame check: Observe burner flames through the sight glass. Very small, lazy, or yellow flames indicate a gas or combustion issue.
- 4. Professional adjustment: Have an HVAC technician measure inlet and manifold gas pressure, clean burner orifices, and verify correct orifice sizing for natural gas or LP.
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Repair Difficulty
Professional Required
5/5
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