Volvo Repair: Air Conditioner, volvo 940, national chains

Question
My wife drives an 95 Volvo 940,the A/C stopped blowing cold air, I checked under the hood,and I noticed that the compressor was not turning,So we took it to a national chain repair shop for a dianostic check,And he stated after working on the car for about 6 hours that no electrical was reaching the compressor,that the problem could the A/C Module or some other sensor could you help me with this,and also tell me where the A/C module is located. And what sensors would be involved.     THANKING U N  ADVANCE

Answer
Bruce, those national chains are something eh?  I could have saved you time and money by telling you that inside the A/C head is a bad solder joint that can be fixed.  This is a common problem on the 940's.  I fix one a week usually.
I suggest a Volvo shop next time because you know they are going to want the 6 hours trying to figure it out.  Roger