TKOPerformance wrote:

If you do not have the original AC/heater box in good condition then I wouldn't even ponder trying to reinstall a factory system.  Every one of those boxes I've seen in the past 20 years has been cracked, shattered, cobbled back together with epoxy, etc.  Its just not worth messing with.  Any modern system is going to be better than 50 year old junk.

A modern compressor is also going to be much better than the old ones that drained like 20-25HP off the engine when engaged and had the weight of a boat anchor all the time.  

 
Good to know.

Replying to the question I have only heard about a local guy who installed one on a classic Mustang and likes the way it performs. Not sure if you'll need to get a bigger alternator.

As Rudi suggests, I'd call an aftermarket A/C system vender, explain what you do have, and see what they have to say.  I have a Vintage Air system, an found them to be quite helpful.  
Remember that the 68 A/C system used R-12 freon, modern systems use a different freon, and the modern freon doesn't work that well witht the components (evaporator, condenser) from 1968. 

Maybe the OP is looking for a fully electric A/C system?  Here's an example - https://mightycarmods.com/blogs/news/cool-runnings-electric-air-conditioning-allows-a-c-in-any-project-car?srsltid=AfmBOorXl53zgo3yEN06-05IjG3hoSmg9ThN-ofdNFxcANjRcuTSqFNm

Wonder if a compressor can be sourced at a Tesla boneyard?

GPatrick wrote:

Maybe the OP is looking for a fully electric A/C system?  Here's an example - https://mightycarmods.com/blogs/news/cool-runnings-electric-air-conditioning-allows-a-c-in-any-project-car?srsltid=AfmBOorXl53zgo3yEN06-05IjG3hoSmg9ThN-ofdNFxcANjRcuTSqFNm

Wonder if a compressor can be sourced at a Tesla boneyard?

$1,300 for the compressor.  Pulls 100 amps. Compatible with Vintage Air Gen IV in-dash system.  It will double the cost of an AC system, plus a huge alternator, but sounds doable!   We just need to find a junk yard full of dead-battery EV cars to see if one could be bought cheaper. I’m sure there will be lots of those cars in the near future.
I would be game for doing this in my convertible, just so no compressor would have to go on the engine.  But, where would one mount it?

If you have room on your engine for a belt-driven sanden compressor to mount, that would sure simplify things, though

This is yet another reason to run a Fox accessory drive system.  You can pick up a used compressor for that setup for about $50-$150 on eBay.  They are quite simple and can be rebuilt for about an hour's effort and $50-$100 worth of parts, during which you can clean everything so you aren't tied to running conversion oil or R12.  Then hoses can be made to connect that compressor to the other parts of the system whatever they may be.  Its so common I would bet that those hoses are already available from the major AC system suppliers.  

So I think really what you are considering is a system that eliminates the vacuum and/or cable controls in favor of electric.  You have a couple options.  If your existing box is okay then the system can be fixed, and you can simply add a newer style compressor to that system, and convert it to R134a.  This would really just require some hoses, though a condenser made for R134a (6 pass) probably isn't a bad idea, and there may be some other work converting to R134a depending on the compressor you use and what's in the system now as far as oil.  

The big thing with the old system in my mind is not to throw good money after bad.  

This is the first time I've seen these things, so this is new to me. The videos above in post 14 are brutally honest. He used a 12,000 BTU compressor which needs a 100A fuse. He GUESSES it runs at about 60A at 12v. He has no way to measure the actual power requirements. He already has a very large 150A alternator. For reference the 1G alternator that came in my 69 Mach is 55A.
The blower at the evaporator (in the cabin) was only 300cfm and was not adequate. He ran it for one hour with the engine off, and the voltage dropped to 11.4v and it shut itself off. That was below the threshold for his engine electronics (Holley EFI?). 
To be happy it needed a bigger blower to circulate more cfm in the cabin, so he changed this to 600cfm (which sucks even more power). He also changed the fan for the condenser from 233 cfm to 1400 cfm (requires even more power).  He kept stressing that the power requirements are intense and it needs a BIG (dare I say huge) charging system. He added a second battery in the trunk just to run the AC and used some impressive cables.
All of this was by the seat of his pants. He didn't know how much power it used to start with, or how much more he added. I would use a more traditional approach with a Sanden compressor. Just my $0.02

BobE wrote:

TKOPerformance wrote:

So I think really what you are considering is a system that eliminates the vacuum and/or cable controls in favor of electric.  You have a couple options.  If your existing box is okay then the system can be fixed, and you can simply add a newer style compressor to that system, and convert it to R134a.  This would really just require some hoses, though a condenser made for R134a (6 pass) probably isn't a bad idea, and there may be some other work converting to R134a depending on the compressor you use and what's in the system now as far as oil.  

The big thing with the old system in my mind is not to throw good money after bad.  

While the condenser is one item to verify, the original installed evaporator, dryer, type of oil used, and higher pressures of the R-134 system should be verified to be compatible with the original system.
I did convert my 86 Bronco from R-12 to R-134 and found while it cooled “well enough”, it wasn’t as cold as with the R-12.
Suggest calling Vintage Air, or another vender, for their input. 
 

I spoke to Classic Auto Air about it years ago and the summation of their advice was switch the condenser, hoses (due to molecule size making the old R12 hoses porous with R134a), and flush the evaporator.  This assumes running a modern compressor (Sanden, etc.).  Then fill the system with PAG oil and charge it with R134a.  

One thing to consider on an R12 to R134a conversion is that the high pressure switch needs to be adjusted.  This is often left out of instructions, but is essential for proper system performance.  The switches have a small straight slot screw between the terminals (you must unplug the connector to see/access it).  If you try to cycle the compressor in an R134a system at the R12 cycling pressure it under performs.