My '99 C70 AC starts working fine, then starts to blow hot. From the forums I have determined that the compressor clutch needs to be shimmed, and have arranged to have that done. But my problem goes beyond that. When set to "Auto", the fan will erratically alter both air speed and direction. This problem occurs whether or not the temperature is calling for AC. I can keep this from happening by putting the fan in the manual position. In addition to clutch work on the compressor, do I need to switch out the three-knobbed AC controls in the dash? This is a sweet car; if I can get the AC working right, it is essentially as new. Thanks for the help.

 

The A/C repair tech should ensure all controls are working properly. Also give you a warranty for the work. Get another switch from a junk yard and try it!
Good luck!