Why not run it in the other direction? Peltier Coolers can generate small amounts of electricity through heat absorbtion-not enough to power a compressor unless you flood your engine bay with them at an impractical cost in money and space, BUT a few coolers would be more than enough to trigger some vent fans in the passenger compartment, with an 'off; switch that would shunt the current to a few hidden LEDs just to allow the Peltiers to continue working...
What about a few coolers for the passenger fans, a few more for the radiator fan...two self-regulating, self-powered systems working independently from the main harness, cutting parastic load...which let's you use a normal AC with more efficiency IF you want to...
I don't have the spare cash to try it on my trusty Red Menace (1993 Ford Festiva)-also, I have no AC and never felt the need for one.
Any of the more Tech-minded members want to crunch some numbers/grab some voltmeters and see if it might be worthwhile?