2ND MAINTENACE TUNE-UP FOR 4YR HEATING SYSTEM. CLEAN AND CHECK BURNERS AND BURNER OPERATION. CHECK AIR FILTER, THERMOSTAT, ENERGY CONSUMPTION, HEAT EXCHANGER, HIGH LIMIT CONTROL, HUMIDIFIER, FAN CONTROL, AND ALL ELECTRICAL CONNECTIONS. CHECK GAS PRESSURE AND FOR PROPER VENTING. ADJUST BLOWER COMPONENT, AND LUBRICATE NECESSARY MOVING PARTS.