got my 91 dakota which im assuming has AC. The guy that i got it from said that it has never worked and he never did try and get it fix. When i was going through the engine i noticed that it seems like there is a belt missing on what appears to be the AC pump. how many belt am i supposed to have on a stock 91 dakota sport 3.9 engine? I remember having seen 3, should there be a fourth one?
If am right and that is the AC pump, will it still work after not being used or even turned for years?

 

If your A/C system hasn't been used for years, I'd bet that the seals are cracked or broken by now. Freon had a lubricant added to it that lubed the A/C seals. That's the reason many owners manuals advised running the A/C every few weeks, even in the winter, to keep the seals from drying out.

Dusty

 

I'd bet its the A/C pump (I believe its located on the driver's side of the enigne, up on the top, with some lines running to it).
The A/C compressor probably stopped working, so they installed a non-A/C belt on it.
You could install the longer belt (the one for your engine with A/C), but I doubt the system will work correctly, since people don't usually just take the belts off because the A/C system is working fine.
Also, your A/C system uses R-12, which you can't buy, and only licensed A/C shops can purchase and use. Although there are conversion kits.
But like Dusty said, there are probably other problems with the A/C system.

 

I would almost take your AC compressor out and rework the seals inside. This is laid out in the factory service manual.Youshould be able to understand the proceedure.