Status LED flashes six times, furnace locks out and will not heat

Safety first: Disconnect power before accessing internal components. Be cautious of sharp sheet metal edges.

Steps to check:

• Inspect condensate system: For high-efficiency Gibson furnaces, remove and flush the condensate trap and hoses. Ensure proper slope to the drain and no kinks in tubing.
• Check vent pitch and support: Verify PVC vent pipes slope back toward the furnace (for condensing models) and are properly supported. Sagging pipes can collect water and intermittently block airflow.
• Observe operation: Restore power and call for heat. Watch the inducer and listen for changes in sound just before shutdown. If the inducer slows or surges, it may be failing.
• Have a technician measure: A professional should measure draft and pressure switch operation under load to determine if the switch or inducer needs replacement.