F06
Westinghouse
Limit circuit open or wiring fault
Furnace shows F06; blower may run at high speed continuously.
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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 auxiliary limit on blower deck, Broken wire in limit circuit, Loose spade connector on limit string
How to Fix / Troubleshooting
Safety: Turn off power before accessing internal wiring.
Steps:
- Locate all limit switches in the furnace: main high limit on the heat exchanger panel and any auxiliary limits on the blower deck or vestibule.
- With power OFF, check continuity across each limit switch. Replace any that are open at room temperature and not manual-reset type.
- Inspect the wiring daisy-chaining the limits back to the IFC; repair any broken or overheated wires.
- Ensure connectors are tight and not oxidized.
- After repairs, restore power and verify that the blower returns to normal operation and F06 clears.
Note: If limits are opening due to overheating, address airflow or combustion issues, not just the switches.
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Repair Difficulty
Medium
3/5
Required Part
High Limit Switch
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