Sorry.  I didn't know where to put this (engine would probably be more logical but not in this case...).  Well, I have a YJ and I don't know if the saharas or islanders  or rio grandes have air conditioning, but I have the S model 2.5l and it doesn't.  Well, needless to say, it's not the most fun vehicle to drive on the highway (as most of you know).  I was wondering if any of you know of any decent air conditioning units that plug in to the cigarette lighter outlet.  I thought about actually buying an a/c unit but the horse power it will draw, while seemingly insignificant, is vital as the engine doesn't have enough to give.  Well, tell me what you guys know.  Thanks!  

The OEM AC system hangs below the dash. I have actually put one in a '92 YJ from the junk yard. It was pretty easy.

Complete ready to go systems cost about 800 to 1000 dollars.

You can get what you need from the junkyard for $100. But, you will need a new dryer ($100). When looking for one in the junkyard, don't get one that has been open to the air. Dirt gets in the system and destroys the compressor. It seems impossible to clean it out and you just keep buyng compressors.

Remember you can't get something from nothing. It takes the same energy to create electricity to run an ac unit as it takes to just run the ac unit. In fact, probably more, because nothing runs at 100% efficiency.

So, the most efficient ac system for your motor would not be electric.