I have a 2001 Saab 9-3, that needed to have the AC compressor replaced. Trying to save a little bit of money (because a new one cost $400), I purchased a re-manufactured one off of Ebay. My dad put the compressor in for me, and everything seems good, the grinding noise is gone but now my AC doesn't work anymore. This is the first time my dad has ever replaced an AC compressor and I was wondering if this could be caused by something he did wrong putting it in (he thought maybe he didn't put enough coolant in), or if something is wrong with the actual unit I purchased. Thanks!