Lennox Equipment not specified Error Code 228

Priority condition: Service Soon The furnace control is not able to calibrate the pressure switch. Unable to perform pressure switch calibration. • Inspect vent for blockage and combustion air inducer for correct operation and restriction. • Check for blocked cold end heater box or condensate drain or drain strainers at outlet of cold end heater box (CEHB). • Check for cracked hoses. • Check levelness of unit. NOTE: Check Service Manual and Service and Application Note H-13-07 “Condensing Furnace Pressure Switch Troubleshooting” for additional information.