I have a friend who is a real AC guru. The guy's a whiz at doing AC retrofits in his old cars and his systems are really reliable and work well. It's nice riding in his early 60's cars with the AC blowing cold
He's a DIY guy and has mostly uses junkyard parts for his systems. He's one of those super clever guys that I WISH I could be more like!
Anyway, he's NOT a fan of the R4 compressor and seems to be in love with the V5. He's had some failures with new R4's and just generally doesn't like the radial design and the fact that it's not serviceable. He's rebuilt the V5's and says it's not difficult at all and can be done for about $20.
The main hitch with a swap would be dealing with the oil cooler lines which are bolted to the compressor bracket, plus building a bracket for the V5 that isn't a belt slinger
It's just something I was thinking about. For now my AC is working well so I'm not fooling with it until I have too! Even then I'm not sure if a swap to a V5 would be worth the trouble. Just food for thought...
The V5 pump is a 5 cylinder with a "wobble plate" behind the clutch which changes the stroke of the pistons based on the high/low side pressures. This is how the variable displacement part works and my friend says it's really simple and reliable. Seems like it would work pretty well with the ACC because the compressor is always on with the R4 system (Unless the switch is "off") and it uses the heater core to "overpower" the evaporator when heat is needed. With the R4 the compressor just runs wide open all the time but the V5 has the ability to "back off" some when the pressure isn't needed.
All this is just advice from a person who's worked the kinks out of systems and has decided what works for him. He flat out said that he wouldn't have worked on the ACC system for more than an hour before just starting over without the servo, sniffer and computer.
He was pretty unimpressed with the ACC system in general just because of the complexity. I think that's what gives it a lot of it's charm though!