[jeff5may]

If you want to do something like that, just go to a pull a part salvage yard and start looking. My favorite vehicles for this are the minivans and SUV crossover mutts with rear air. The air handler for the rear air is in a super easy to remove area of a rear quarter panel in front of the tail lights. The things connect with brake line (double flare) or power steering (parallel thread plus o-ring) fittings. Most all have a txv included, sized for the evaporator and blower. They also have a drain pan and rubber hose. They work really well with refrigerator compressors. You should be able to get out of there with all the stuff you need for 30 bucks or so.

Since you already have a donor air conditioner and expansion valve, why not run what you brung? The evaporator, fan, and such is already matching. Just remove the condenser and its fan blade and rig up your passive heater piping. The fan motor in those units pulls 150 Watts or so, but reduced motor power gets you less airflow and the resulting block of ice for an evaporator.