Furnace will not start, inducer fan does not run, display shows E03 shortly after a heat call.

Safety: Turn off electrical power and gas supply before removing panels. Combustion air and venting issues can cause carbon monoxide hazards.

Steps:

• Check vent and intake: Inspect the Atlantic furnace flue pipe and combustion air intake (if direct vent) for obstructions such as leaves, nests, snow, or ice. Clear any blockage.
• Inspect inducer motor: Remove the upper front panel and locate the draft inducer assembly. Spin the fan wheel by hand (with power off); it should turn freely without scraping. Look for water in the housing or rust.
• Check pressure switch tubing: Ensure the silicone tubing from the inducer housing to the pressure switch is not cracked, kinked, or filled with water. Replace damaged tubing and clear any condensate traps.
• Test pressure switch: With a multimeter (and power off), check continuity across the pressure switch terminals. It should be open with no draft and close when the inducer runs. If it never closes even with a clear vent and running inducer, the switch may be faulty.
• Inducer power: If the inducer never starts, verify that the Atlantic control board is sending power to the inducer motor during a call for heat. This test involves live voltage and should be done only by a qualified person.

Warning: Do not bypass or jumper the pressure switch for normal operation. This is a critical safety device.