Status LED shows 2 flashes, furnace will not start or shuts down quickly after starting.

Safety: Turn off power before removing furnace doors. Do not bypass the pressure switch for operation; it is a safety device.

Steps to check:

• Inspect pressure switch tubing: Locate the rubber hose from the inducer housing to the pressure switch. Remove it and blow through it to ensure it is clear. Check for water, cracks, or kinks. Reinstall firmly on both ports.
• Check venting for blockage: For Ruud condensing furnaces with PVC vent, inspect intake and exhaust terminations outside for leaves, nests, snow, or ice. Clear any obstructions.
• Test pressure switch operation: With power off, disconnect one wire from the pressure switch and check continuity across the terminals with a multimeter. With no inducer running, the switch should be open. If it reads closed, the switch is stuck and should be replaced.
• Inspect inducer relay on control board: If the inducer runs when it should be off, the relay on the integrated furnace control (IFC) may be stuck. This requires board replacement by a qualified technician.