FIRST CLEAN AND CHECK ON 5YR HEATING UNIT UNDER SERVICE AGREEMENT. CHECK THERMOSTAT, AND AIR FILTER. CLEAN AND CHECK BURNERS AND BURNER OPERATION. LUBRICATE ALL NECESSARY MOVING PARTS, AND ADJUST BLOWER COMPONENTS. CHECK HEAT EXCHANGER, HIGH LIMIT CONTROL, FAN CONTROL, HUMIDIFIER, GAS PRESSURE, AND ALL ELECTRICAL CONNECTIONS.