[bhill86]

I installed a Classic Auto Air system in my 77 400 being in a similar situation as you. I was missing all components beyond the evaporator core but flushed mine, it had no holes and everything under the dash was present and worked well.

I did not want to use a vintage air system (though people seem to like it) because I had all of the above mentioned items in working order already. I also don’t like the idea of tube ducting vs the factory stuff not to mention the hassle of replacing everything. I don’t believe at the time VA offered a retrofit kit for an AC car but you might be able to buy the components individually.

That said, I opted for the CAA Kit. It included the compressor (modern sanden), all of the lines, the accumulator/drier and a parallel flow condenser. It’s also 134a and it ran me around $1200 I think. Installation was fairly easy but I have some gripes in the fit and finish department. The compressor bracket is ugly and unpainted. I still need to remove and paint mine. The design of the bracket isn’t ideal either. I had really bad belt flutter initially. That seems to have corrected itself after some time. I also made a small pedestal bracket to add some rigidity to the compressor. I’m not sure how much that helped or didn’t.

The hard lines they provided didn’t fit the best either. I’d have to go back to my TAC post if it’s still there to recall exactly what the issues were but I remember one hard line was too long, one hose was almost too short.

Lastly, the charge was a little tricky to get right. It’s possible a competent AC shop could perfect it but I opted to charge myself since I was getting quotes of $200 to fill the system. It does blow cold but I think there is room for improvement. One thing I would’ve don’t differently was install a variable orifice tube instead of a fixed.

I should note that Vintage air sells a different compressor bracket that looks like it would work better that could be used with the CAA setup I believe. I planned to try that but opted not to since my belt flutter seemed to disappear.

CAA’s customer service was also severely lacking but this was around COVID times or just after the peak so I’ll make an assumption that is part of the cause and hopefully things have gotten better.

Hope this provides some insight.

[hgerhardt]

Since the under-dash parts and evap are the most complex sub-assembly of all, I'd use that and piece together the rest of the parts underhood.

To avoid the aftermarket, kludgy compressor/mount, I'd use a junkyard Olds compressor mount for an A6 and get a new A6 from Alma Products who now has the GM tooling for that compressor. Make sure the compressor has PAG oil in it if going R-134a. I'd also get a parallel-flow condenser.

Yeah, the A6 is heavier than a Sanden, etc, but it'll last forever and look "correct", as well as have good belt alignment.