The furnace indicates a condensate fault; the unit shuts down during operation (condensing models).

Safety: Turn off the power. Be prepared for water spillage when opening the condensate trap.

• Inspect drain line: Trace the condensate hose from the IVT furnace to the drain. Look for kinks, sags filled with water, or freezing in unheated spaces. Straighten or thaw it as needed.
• Clean condensate trap: Remove the trap assembly according to the IVT manual. Flush it with clean water to remove sludge, scale, or debris. Reassemble, ensuring all seals are tight.
• Check level switch: If equipped, inspect the condensate float or level sensor for free movement and clean any slime buildup.
• Prime trap: Before restarting, pour some clean water into the trap to ensure a proper water seal.

Ensure the condensate line has a continuous downward slope to the drain. If the fault persists, have a technician check for internal heat exchanger blockage.