97 freightliner ac

Ok guys I replaced the compressor on my 97 freightliner last year cummins m11 ..reason was in put a hole in the old compressor pulling on it ..so put new compressor had it charged by a guy that's certified..now if I'm idling the compressor will stop turning unless I have my manual fan running never had to run it before..sometimes I think it stops going downthe road cause it blows warm for a few minutes..I turn it off for a few back on its cold as ice again..if idling no manual fan on it will stop completely and burn the belt ..what's going on..I think it's air in the system but not sure

 

Thanks guys I'll pick 1 up.will I lose my charge when changing it out