Furnace attempts to start but shuts down; LED shows code 32 (pressure switch stuck closed).

Safety: Disconnect power before touching wiring or components.

Steps:

• Inspect wiring: Compare pressure switch wiring to the Keeprite wiring diagram on the blower door. Correct any miswired connections.
• Check for moisture: Remove the pressure switch tubing and inspect for water. If water is present, clean the condensate trap and drain, then dry or replace the tubing.
• Test switch continuity: With the furnace off and inducer not running, use a multimeter to check continuity across the pressure switch terminals. It should be open. If it reads closed, the switch is stuck and must be replaced.
• Check inducer relay: If the inducer runs constantly even with no call for heat, the control board relay may be stuck closed, falsely keeping the pressure switch closed. This requires board replacement by a technician.

Do not operate the furnace with a known defective pressure switch. Replace the switch with the exact Keeprite-specified part number.