Lennox Error Code 250

Priority condition: Service Soon The furnace primary limit switch is open. If limit switch is not closed within three minutes, the unit will go into a 60 minute soft lockout (Watchguard mode). Perform the following: • Check for high gas pressure. • Check for low supply air. Low supply air due to being plugged or restriction in system (example: dirty air filter or blockage in duct work). • Check for proper firing rate on furnace. • Check for non-functioning zone dampers. NOTE: Limit trips will place the iHarmony zoning system into non-zone mode. NOTE: See ACC-14-01 for further details.