Furnace shows E03, flue fan may run continuously or not at all

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

Faulty air pressure switch, Blocked flue, Defective flue fan, Pressure tubing issues

Safety: Switch off power and gas. Flue faults can be dangerous.

Inspect flue and terminals: Check for obstructions and damage as described for A05.
Check pressure switch and tubing: Ensure tubes are intact and properly connected to the fan and switch. Replace any hardened or cracked tubes.
Test fan operation: Restore power and call for heat. If the fan does not start or is very noisy, it may need replacement.

If E03 persists, a technician should test the pressure switch and fan with proper instruments.

Hard 4/5

Air Pressure Switch

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