Furnace displays E3 and shuts down shortly after the inducer starts

Safety first: Turn OFF power and gas before removing vent or drain components. Avoid running the furnace with venting disconnected.

• Inspect vent and intake: Go outside and check the furnace exhaust and intake terminations. Remove any leaves, snow, bird nests, or insect screens clogged with debris.
• Check pressure tubing: Open the blower door and locate the rubber or silicone tube from the inducer housing to the pressure switch. Ensure it is firmly connected at both ends, not cracked, kinked, or filled with water. Replace if brittle.
• Clear condensate trap: On high-efficiency Kelvinator furnaces, remove the condensate trap and flush it with warm water to clear sludge. Ensure the drain line slopes downward and is not frozen or blocked.
• Gently tap the pressure switch: With power OFF, lightly tap the pressure switch body to free a stuck diaphragm. Do not hit hard or deform the housing.
• Test operation: Restore power and call for heat. If E3 persists after clearing venting and tubing, the pressure switch may be defective and should be replaced with the correct Kelvinator-rated switch.
• Do NOT bypass: Never permanently jumper or bypass a pressure switch; this is unsafe and can lead to carbon monoxide hazards.