Heater & A/C control

the aftermarket systems use a smaller reciprocating compressorl like a Nipendenso or whatever. Weighs a lot let that the RV2 but is disposable too where the rv2 might be rebuilt. Aftermarket will probably use a fixed orafice tube between low and high sides rather that the old expansion valve also. Those differences being under the hood. Inside the car aftermarket a/c is just that. Seperate fan control, etc,, and you'll still need the factory components to get heat and defrost.
I intend to purchase brackets and such to relocate and run the smaller compressor with the stock interior workings.