Here's the situation. I'm restoring a 1970 BBC Chevelle which has factory AC. The car is completely gutted at this time. I've purchased a March pulley conversion kit which includes a Sanden AC compressor. I was planning on replacing the factory AC system with a newer and more modern Hot Rod Air system. That way, I can run it along with the Sanden and upgraded hoses for R134. This way, I can also smooth out the firewall while everythings apart for a cleaner look.

I recently thought about it and had second thoughts. I figured if I stayed with the factory set up inside the car, I can just upgrade the hoses and plumb it to the Sanden compressor. Going this route, I can save a little money by not having to purchase the Hot Rod Air system and keep the factory appearance inside the car. Keeping it stock inside will be easier to hook everything up with no fabricating needed.

Anyone here on the forum gone through the same process or done anything similar? Any recommendations as to which route to go?

You will need a few more bits to convert the oem A/C to R134. I would call one of the outfits that provide replacement parts and check on details and costs.

Probably the biggest downside to using the oem A/C evaporator hardware is the amount of engine compartment space it takes up. That is one considerably large bulge they hang off of the firewall. On the plus side is the fresh air intake on the system. NONE of the aftermarket systems provide fresh air, only recirculate for both heat and cool.

I am in the process of putting A/C into my '68 El Camino non-A/C car. I started with a VA Sure-Fit and changed to a Classic Auto Air Perfect-Fit system. It turns out to be a better base for my customizations... because when I am done it will use the OEM control panel in a modern configuration (first lever = fan speed, second lever = temp, third lever = mode control). Modes will include max A/C (recirculate), A/C (fresh), vent, heat, and defrost. I have done some control system engineering and vacuum form plastic fabrication to achieve this. And still have some work to go. Someday I will have a web page to cover it all...

From a value standpoint, keeping the original system in place would be a plus, especially since it is an original big block car. Using the aftermarket system certainly saves weight and space. Depends if your'e more into restoration or restification. Good luck with your project!