Inducer runs but the ignitor does not warm up

What is going on

The inducer comes on with a heat call but the ignitor never glows and no flame follows. The control flashes the pressure switch code about 2.5 minutes after the call.

Likely causes

• Prove switch tubing routed wrong, blocked, leaking or holding condensate
• Low differential pressure from a blocked intake or exhaust or wrong vent sizing
• Wrong or out-of-calibration prove switch
• Loose or wrong wiring at the prove switch
• Prove switch failed

Check in this order

1. Turn off power at the disconnect before touching wiring or components.
2. Check the tubing for correct routing, obstructions, leaks and condensate.
3. Check the differential pressure across the switch against the set point on the switch.
4. Check intake and exhaust for blockage and check vent size and length.
5. Check the right switch is installed and its wiring is tight. Replace the switch if all else checks out.

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