peltier elements aren't a viable option IMHO, they are an added load on the electrical system, and to make them useful in any way for cooling you need to have a heat sink on the opposite side to dissipate the heat to somewhere outside the car or the element will do you no good at all, i've messed around with them before and honestly i would spend the extra time and money for an A/C unit plus install than try to make peltier elements work for cooling a vehicle. they work good for spot cooling (ie. a cupholder cooling set up) but not for large volume cooling
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