I just purchased a 1997 MK111 with 100,000kms on it. When I select Max Air conditioning I just get hot air blowing out of it. I had it set on Vent only and once had cold air blowing but as soon as I turned it off and on again the no cold air just hot. I can see the AC compressor is frosted up and seems to be working. Any help would be appreicated. Richard