FIRST CLEAN AND CHECK FOR 12 YR HEATING UNIT UNDER SERVICE AGREEMENT. CHECK ALL ELECTRICAL CONNECTIONS. CLEAN AND CHECK BURNERS AND BURNER OPERATION. ADJUST BLOWER COMPONENTS, AND LUBRICATE ALL NECESSARY MOVING PARTS. CHECK THERMOSTAT, AIR FILTER, AIRFLOW, HUMIDIFIER, HEAT EXCHANGER, HIGH LIMIT CONTROL, HUMIDIFIER, AND GAS PRESSURE AND FOR PROPER VENTING.