Heil furnace LED flashes 2 times; inducer runs but burners do not light, or furnace shuts down shortly after starting.

Safety: Turn off power before opening the blower or burner compartment. Do not bypass the pressure switch for operation; it is a critical safety device.

Steps to check:

• Locate the pressure switch: Round or oval device with two wires and one or two rubber tubes, mounted near the inducer assembly.
• Inspect tubing: Remove the rubber hose(s) from the pressure switch and inducer port. Check for water, debris, or cracks. Blow gently through the tubing to clear any blockage. Reconnect firmly.
• Check switch operation: With power off, disconnect the wires and use a multimeter on continuity. At rest (no inducer running), the switch should be open. If it reads closed, the switch is stuck and should be replaced.
• Check venting: Make sure the PVC exhaust and intake pipes (if 90%+ Heil furnace) are not blocked by ice, leaves, or nests. Clear any obstructions.
• Reset and test: Restore power, call for heat, and observe if the error clears.

When to call a pro: If the pressure switch tests closed at rest or does not change state with inducer operation, or if you suspect incorrect vent sizing, have a professional evaluate and replace the switch or correct venting.