Hi, just thought I would add my 5 cents. My previous A4 had a faulty pressure switch (G65) this meant the econ light was on all the time, I bought one from audi (£45 ish) and fitted myself, no gas leaks when fitting. The air con on my current A4 wasn't cooling but the econ light was still going on and off, I tried to listen for the comressor kicking in when stationary but couldn't hear anything, I took it to an air-con man last night, he initially thought it was the compressor, but then checked and it just needed re-gassed. so all is working fine today and all for £50. I checked the car with vag-com last week and there were no errors. Hope that helps someone. ps. is the G65 switch is gone it will throw a code on vag-com. get it checked first.