York furnace starts inducer, but pressure switch does not close; LED shows 2 flashes.

Safety: Turn off power to the furnace before working inside. For condensing (PVC vented) York furnaces, also be prepared for water in the condensate lines.

• Inspect venting: Go outside and check the PVC intake and exhaust pipes for leaves, snow, ice, bird nests, or debris. Clear any blockage fully.
• Check pressure switch tubing: Remove the front panel. Locate the round pressure switch and its rubber tubing to the inducer or collector box. Ensure the tubing is not cracked, kinked, or full of water. Blow gently through the tubing to clear any moisture or debris, then reconnect securely.
• Clean condensate trap: On high-efficiency York furnaces, locate the plastic condensate trap assembly. Remove hoses and flush the trap with warm water until clear. Reconnect hoses firmly and ensure proper slope to the drain.
• Test operation: Restore power and call for heat. Watch if the inducer starts and if the furnace proceeds to ignition. If the code persists and venting is clear, the pressure switch may be weak or out of calibration.
• Professional help: Replacement of the pressure switch must match the York part number and rating. A technician can verify proper draft and switch operation with a manometer.