What about Exhaust heat powered air conditioning?
 

Pretty much like propane gas refrigerators
Only using exhaust heat instead of propane gas as the heat source?

HowStuffWorks "Gas and Propane Refrigerators"
Absorption refrigerator - Wikipedia, the free encyclopedia

Draw back is that they tend to be heavy, bulky and they don't like being moved and the refrigerant is very flammable and under a great deal of pressure.
RV's tend to use absorption refrigeration in their fridges and when something goes wrong with it the common fix is to pull the unit, flip it on to it's top and leave it like that for a day or two, much harder to do that with a car.

Years ago I was on a caboose that had a combination electric/gas refrigerator on it, it didn't seem that bulky. It would have been a whole lot harder to turn over a caboose than a car.:D Chumly

People want to be be cool even at idle. The A/C will need a few hp to work, but at idle there isn't that much heat available.
-mort

Trains and RV's tend to have a lot more bulk to them and are a lot smoother then passenger cars.
LP fridges tend to have very thick heavy coils while compressor refrigeration tends to have much thinner coils, I assume that this is part of the reason for the increased cost in an absorption fridge, but if you want to make one your self they are not that hard, just be careful not to get your self killed.

[QUOTE=Ryland;317461]Trains and RV's tend to have a lot more bulk to them and are a lot smoother then passenger cars.
Are you kidding? Apparently you have never ridden a caboose on the rear of an 80-130 car freight train. I have been
knocked down by the slack running in and shortly after stood back up when it ran out (luckily the train didn't break in two).:eek: True, they have more bulk but most autos ride much better unless you are comparing to a passenger car.

What RR still runs cabooses?

Then build one and put it in a car! they are a really simple system, they just don't like to be sloshed around much and even in a train when the fridge stops working you can pull it out and flip it over because they tend to be built as a unit that can be removed.

I grew up with an LP fridge and have helped a hand full of people out with theirs, we also own an Icy Ball, it's a very crude simple absorption cooler that you can heat up on your stove top, really neat but people are freaked out because they can blow up.

Believe it or not but the Union Pacific did on certain locals at least until 2006 when I got disabled. Most cabooses were eliminated in the 80's when they railroads were deregulated and they came up with Fred (F***ing rear end device). Chumly