AC compatibility between 308 and Mondial? AC upgrade suggestions?

Dave, the Mondial's HVAC is more powerful than the 308's for the additional interior volume and glass area so requires a larger compressor than the 308. You can see that when you compare the compressor specs of the 2 cars.
So the 308 replacement systems wouldn't just "fit"; its compressor would need to run a lot more to supply the rest of the system.
Additionally, the control logic of the ECU isn't adapted to the smaller output compressor.

 

I have worked on cars with the retro air system and was not impressed. I couldn't tell the difference. The compressor installation is very bush league. Going to a Sanden compressor is in itself a good idea but not how they did it. I'd get the parts from a Mondial mount and do the very slight mods required to make it fit the smaller compressor the 308 needs. Putting in a new, straight, clean, more efficient condensor with some very powerful fans isn't a bad idea either but that is more of a maintenance item at this point in the cars life anyway. I almost never see a 308 with an original condensor that is still capable of doing the job anymore. Old, corroded, bent fins are not much of a heat exchanger.

Their system also uses R134. I think that alone is a bad idea.

 

The OP has a Mondial as I understand, so needs a bigger compressor than the 308 kits offer.

 

Dave, check https://www.ferrarichat.com/forum/threads/some-tlc-for-my-qv.482046/ post#57

 

Then there is better than a 50% chance he has the best possible compressor anyway.,

 

If you have the round compressor, you have the best thing going. It it is square buy a setup off a later Mondial. As far as any of the other parts the car was kind of built around them. Old corroded, bent up condensers will not work very well and new should be considered. Don't be talked into conversion to R 134.

 

You'll find a lot of answers in my thread