Status LED flashes three times, blower may run but burners do not light.

Safety First: Disconnect power before removing wires or tubing from the pressure switch or control board.

This code means the control board sees the pressure switch closed when it should be open (before inducer starts).

• Inspect tubing routing: Ensure the pressure switch tube is connected only between the inducer port and the pressure switch. It should not be connected to any other source of pressure or vacuum.
• Check for water in tubing: Remove the tube and look for condensate. Drain and dry the tube if water is present, and verify the condensate drain system is not backing up.
• Test pressure switch: With power off, disconnect the wires and check continuity across the switch. It should be open (no continuity) when the inducer is off. If it reads closed, replace the pressure switch.
• Inspect inducer motor: Verify the inducer wheel spins freely by hand. If seized or noisy, the motor may be failing and causing abnormal pressure conditions.
• Reset control: After corrections, restore power and call for heat to see if the code clears.

When to call a professional: If the pressure switch tests good but the board still reports it stuck closed, the integrated furnace control may be faulty and should be diagnosed by a technician.