1ST SA ON 6YR HEATING UNIT. CHECK THERMOSTAT, AND AIR FILTER. CLEAN AND CHECK BURNERS AND BURNER OPERATION. CHECK HEAT EXCHANGER, HIGH LIMIT CONTROL, HUMIDIFIER, FAN CONTROL, ENERGY CONSUMPTION, GAS PRESSURE, AND VENTING. CHECK ALL ELECTRICAL CONNECTIONS. LUBRICATE ALL NECESSARY MOVING PARTS, AND ADJUST BLOWER COMPONENTS.