CHECK HEATING UNIT TO MAKE SURE EVERYTHING IS FUNCTIONING PROPERLY. CHECK THERMOSTAT, AIR FILTER HEAT EXCHANGER, HIGH LIMIT CONTROL, PROPER ENERGY CONSUMPTION, HUMIDIFIER, AND GAS PRESSURE AND FOR PROPER VENTING. CLEAN AND CHECK BURNERS AND BURNER OPERATION. ADJUST BLOWER COMPONENTS, AND LUBRICATE ALL NECESSARY MOVING PARTS.