So I bought my 09 GT last year and it has always had a knocking in the floorboard every once in a while after a cold start. The noise is loud enough that my friends have asked me, "what they HELL" was that. I took it to the dealer a couple of times with no luck. While changing my oil I noticed that the noise was actually the a/c drier trying to "jump" out of the car. So I took it back to the dealer and this is what they told me. After talking to their tech line the found out that I have an anti-blockage a/c compressor. This compressor supposedly builds up pressure and then releases it to "clear the system". Their tech line told me that I would just have to learn to deal with it. Well, needless to say I don't think I should learn to deal with it when I paid as much as I did for this car. Anybody know if this is true and if so what I can do to dampen the noise?

 

A/C drier? Anti-blockage A/C compressor? Wha? Who?

 

Ummmm I think its time for a second dealer. That sounds like BS.

 

What would it be clearing that is causing a blockage?

 

Supposedly it is to prevent the oil from settling in one spot. They called it CASS. Compressor Anti-Slugging Strategy. They gave some sheet on it.