And you also pull the vacuum to extract any excess moisture from the system. Creating a vacuum essentially lowers the boiling point of water and if you have moisture in your system, you will see it coming out of the vacuum pump as steam. An hour is probably a good amount of time to let it run, but ideally you'd just want to keep going until you don't see any more steam (+ a bit for good measure).

 

I feel , that I still have some pressure left in the system , but my compressor , even on Recir. mode , is making whizzing and whistling noises. I know that , this is not right, but my appointment is set on 11 th. I hope , it will last 'til then, as it is still hot and humid in NJ.

 

Yes, that's correct - I forgot to mention that aspect of the job - actually it's the main reason you are pulling a vacuum to begin with. Good catch!

 

Your system is probably just a little low due to o-ring leakage. Right or wrong, if it were mine, I'd just add about half a can of Freon and see what happens. But if you are seeing oil from the connections then you're definitely experiencing a leak. I don't know how mechanically inclined you are, but you could basically DIY it for a fraction of the cost. I replaced my entire system in a 2002 Acura earlier this summer. Compressor, condenser, receiver drier, expansion valve, all O-rings, Freon - everything for under $250; all brand new. The only thing I wish I would have changed since it was out anyway is the evaporator; that would have been about $30 more, but it looked to be in good shape. FYI, you cant flush these R134A condensors and evaporators anymore, so be warned that they may tell you that when you take it in. They aren't lying.

 

Lots of good info. I'm earmarking this for future AC issues. Thanks