Error 202 appears, furnace starts fan but then shuts down before ignition.

Safety: Turn off power before removing covers. Do not operate the furnace with the flue disconnected.

• Inspect flue and air intake: From outside, check that the concentric flue terminal is not blocked by leaves, snow, or nests. Clear any obstruction. Ensure the flue pipes are correctly assembled and not crushed.
• Check pressure switch tubing: Open the furnace front panel and locate the air pressure switch (round device with two small hoses). Inspect the silicone tubes for cracks, kinks, or disconnections. Refit or replace as needed.
• Clear condensate from tubes: If water is visible in the tubes, remove them and blow through gently to clear. Ensure the condensate trap is not blocked so water does not back up into the fan or tubes.
• Test operation: Restore power and call for heat. If the fan runs but error 202 returns, the pressure switch may not be closing and should be tested and replaced by a technician.