I have a 2004 bluebird sylphy. a/c stopped working,letting off hot air. Took it to the aut shop,there was no gas in that they regassed the a/c did nitrogen and dye checks,no leaks.Then they said it was electronic and they repaired elctronic parts.It worked for about 30 minutes,for the drive back to my office,parked and by the time work ended and I went to drive home I saw a burst of white stuff when I turned it on then nothing.This happened 3 times. Then came on for app 5 minutes just b4 I got home. Went back to them very upset,this time they said it needed an expansion valve and a liquid dryer.didnt trust them so I got 2 more opionions 1 of which said its something from the a/c box but it needs to be checked with a digital tester and the other said,expansion valve,liquid dryer and etc. They had no more time so I went back to the first one,replaced all of that and when I picked up my car again it was working but stopped halfway home. WHAT could be wrong? Please advise