The radiator cooling fan and the air conditioning compressor clutch are operated by a relay. Test the blower motor as described above. The control head can be tested after removing it as described in BODY AND INTERIOR. Make continuity checks at the electrical connections of the control head with the control lever in its ON and OFF positions. Any other testing of the air conditioning system, including the operation of the pressure switches, requires specialized knowledge and equipment, and is beyond the scope of this manual. Servicing by an authorized Volkswagen dealer or other qualified air conditioning shop is highly recommended.