Thread: Using Series III A/C Compressor on a Series II

I'm doing an engine swap into a Fiero with a 3800 SC III from a 2004 Grand Prix. I'm converting the engine to Series II electronics and throttle body for my application.

I heard that "2004 GTP A/C compressor is a variable displacement type. As such it needs no cycling switch and is under PCM control." So, will the Series III A/C compressor work with the Series II electronics?

series 2 compressors are the same, they have an internal bypass valve. the computer does not cycle the clutch, just turns it on when you hit the a/c and off when you dont.

So you're saying that it is not computer controlled, it automatically does it's thing.

Do Grand Prix's have a pressure switch?

yes they use pressure switches, high and low still, but that is only to tell the computer if its allowed to kick on the compressor, and if something is wrong and the pressure is too high, it will kick it out. Otherwise, its internally regulated. Its a V5 compressor, if you want to read more on it. GM has been using them for years.

Ok, so now I know exactly what conversion line I need. This is good.

On the GP, is the PCM directly connected to the pressure switch? To the compressor? What do the A/C controls on the console connect to?

Ok, just read and to correct myself its not a V5, its a cvc, but same thing, does NOT cycle. The computer uses the input from the a/c control center along with the pressure switches to decide whether to kick on the a/c clutch or not.

I hope my A/C controls are compatible with the PCM. I'll have to go to the Fiero forums for that. Thanks for the help.

no problem. there is the other option, just bypass the computer all together and run your own wiring