MAINTENANCE CHECK-UP FOR 6YR HEATING UNIT. CHECK ALL ELECTRICAL CONNECTIONS. CHECK THERMOSTAT, AIR FILTER, HIGH LIMIT CONTROL, HEAT EXCHANGER, HUMIDIFIER, GAS PRESSURE, PROPER VENTING, FAN CONTROL, ENERGY CONSUMPTION, AND AIRFLOW. LUBRICATE ALL NECESSARY MOVING PARTS, AND ADJUST BLOWER COMPONENTS. CLEAN AND CHECK BURNERS AND BURNER OPERATION.