Furnace attempts to start but shuts down quickly; LED shows 2 flashes repeating; inducer may start then stop.

Safety: Turn off power to the furnace before touching wiring or tubing.

Steps:

• Inspect pressure switch tubing: Remove the rubber hose from the pressure switch and inducer port. Check for water, debris, or cracks. Blow through the tubing to clear any blockage. Reconnect firmly.
• Check venting and condensate: For high-efficiency Goodman furnaces, inspect PVC intake and exhaust pipes for obstructions (leaves, nests, ice). Ensure condensate trap and drain lines are not clogged and are sloped properly.
• Test pressure switch contacts: With power off, disconnect the wires from the pressure switch. Use a multimeter on continuity. With no suction applied, the switch should be open. If it reads closed, the switch is stuck and must be replaced.
• Check inducer operation: Restore power and call for heat. Confirm the inducer motor starts only when there is a heat call. If it runs constantly or not at all, the control board or inducer relay may be faulty.

If the pressure switch is stuck closed or fails continuity tests, replace it with the correct Goodman-rated pressure switch. If the new switch behaves the same, have a technician test the control board.