Furnace does not start heating; status LED flashes 2 times repeatedly.

Safety: Turn off power to the furnace before touching internal components.

• Locate the pressure switch: It is a round or oval device with two wires and one or two rubber hoses connected, mounted near the inducer motor.
• Check hose connections: Ensure the rubber tubing is connected correctly and not pinched. Remove the hose and blow gently through it to confirm it is clear.
• Inspect for water in tubing: If condensate has backed up into the hose, drain it and check the condensate trap and drain line for clogs.
• Test switch at rest: With power off and inducer not running, disconnect the wires and use a multimeter on continuity. The switch should be open at rest. If it reads closed, the switch is stuck and should be replaced.
• Check wiring harness: Inspect the two wires from the pressure switch to the control board for shorts or rubbed insulation. Repair or replace as needed.

If the pressure switch tests good but the board still reports stuck closed, the control board may be faulty and should be evaluated by a technician.