I have a VW Passat 2001 V6 and lately my air conditioning system is intermittently not working. I suspect it has something to do with engine management system as when the problem happens, it is straight after acceleration that causes tachometer to dip abnormally. Some suggested compressor problem but I seriously doubt this as when it works it works for a few days without any sign of compressor problem... Can anyone help me? I really don't want to change the compressor and then find out something else is causing the problem.