1ST MAINTENANCE TUNE-UP FOR 4YR HEATING UNIT. CLEAN AND CHECK BURNERS AND BURNER OPERATION. CHECK MANIFOLD GAS PRESSURE AND FOR PROPER VENTING. LUBRICATE ALL NECESSARY MOVING PARTS, ADJUST BLOWER COMPONENTS. CHECK THERMOSTAT, AIR FILTER, AIRFLOW, HUMIDIFIER, ENERGY CONSUMPTION, AND ALL ELECTRICAL CONNECTIONS. CHECK HEAT EXCHANGER, AND HIGH LIMIT CONTROL.