How do you adjust the Air Conditioner Compressor Belt on a 1986 Volvo 240?

The A/C Belt is adjusted (like old VW beetles ) at the crankshaft pulley w/ shims ! Removing shims from behind the front half of the pulley makes the belt tighter ! Yes there are 6 10mm head bolts which should be loosened evenly until the front half of the pulley and the belt can be removed ! Put the old shims on the outside for later use ! KM That belt needs to be very tight too !