I have just purchased a 1997 MK111 with 100,000kms on it. I have a problem with the AC. It only blows hot air even though the vent only selection. I have read about the "Blend door motor temp control" issue. Can anyone suggest if this might be it or how to trouble shoot the system. all the switches seem to work and change the airflow from floor to dash to defrost. AC compressor frosts up and Has good pressure. Thanks Richard