I know guys have kept the fiero compressor when doing there 3800 swap and this is what i intend to do .
I am wondering if this can be done without discharging the system? I will be dropping the stock motor soon and was wondering if its worth the trouble of not discharging the system or if its necessary in order to mount it to the 3800. Thanks

The 88 4 cylinder compressor works because it is already a serpentine belt driven compressor any others would need to be taken apart to change over the drive from V groove belt to serpentine so as long as you can do that with out loosing pressure it could be done..
Just means you would be making the mounting brackets with the engine in place not out side the car where there is more room to work.

Why not the compressor that came with the engine? I have a 99 engine and po used the compressor. It needs the lines cut and welded to work.

sounds like it will be allot easier just to take it off and mount it outside the car. Thanks for the help

Typically when doing a 3800 swap the 3800 ECM is used to control the A/C relay and thus the A/C compressor. To do this you will need the 3 pin A/C pressure transducer somewhere on the high pressure line.

what phonedawgs said. I used a new '85 fiero compressor I had, put the "serpentine setup" off the 3800 compressor on it ( presses off/on with a clutch removal tool) and I had to drill the threads out of where the mounting studs go through. but it's a perfect fit, Belt lines right up and so do the coolant "Lines", but as he said, you gotta install the "3 prong sensor" in the line, so You DO have to lose the Freon.

Sounds like the best thing to do would be to buy a 3800 compressor and use it since I will have to drain the system anyway?
Will any year sires II compressor N/A or S/C work? My engine is from a 00 grand prix. lots of n/a 3800 in U-pull it but no s/c and mostly Buicks

[This message has been edited by crashmydaytona (edited 01-31-2014).]