Volvo Repair: Air Conditioning, volvo 740, ac compressor

Question
I have newly acquired a 1992 Volvo 740 Wagon.  The temperature locally was 74 degrees this past Friday.  I turned on the A/C and it would not engage-nor would the electric fan on the radiator as it usually comes on when the A/C is working properly. After driving for about 20 min and pulling into a service station to refuel I noticed the A/C began to function briefly with very cool air.  Once I was back on the highway it ceased to function once again.  Is this a relay problem? Thanks!

Answer
Hello,
No it is not a relay problem, it is "pump" problem. I mean, the problem is regarding AC Compressor. It is defective. If you can find a repair shop, it can be repaired, or you should be replace it with new one. However, surely please be sure about the AC gas level, it should be okay.
Regards...