High efficiency A-6 a/c compressor

[David Greenburg]

My '60, which already has an A-6 compressor, needs a new one. I've seen a high efficiency replacement advertised that is supposedly lighter and less of a drain on the engine. Does anyone have experience with these?  Surprisingly, they are comparably priced to a standard A-6.

["Cadillac Kid" Greg Surfas 15364]

David,
The "high efficiency" compressor uses less energy because instead of the 12.6 cubic inch (PER REVOLUTION) displacement they only have 10.  What I have been able to find is that they are in fact "clearance'd" for R-134a, and IF you are talking about a smaller car (than our Cadillacs) in a temperate climate and using R-134a, they will work, but with a lot of re-piping of the discharge and suction lines.  If you are using R-12, stick with the A-6 as long as they are available.
Greg Surfas

[David Greenburg]

Greg:

Thanks; certainly helps my understanding.  My car was already converted to 134a, and I do live in a pretty moderate climate (SF Bay Area, where houses generally don't need/have  a/c).  Do you still think the high efficiency compressor would underperform?

[TJ Hopland]

There is a company that is customizing Sanden compressors to replace A6's.   I looked at them a little bit when I was getting the AC going on my car last summer.  I ended up finding a bracket to mount a regular Sanden on my engine so I went that way.  Sanden makes a ton of AC related stuff, mostly industrial but they seem to have become the favorite for aftermarket ac and 'hot rods' so they are fairly easy to find.   The A6 compressor was used on a lot of equipment like tractors well into the 80's so apparently there is a decent aftermarket in keeping that stuff running as well as the automotive applications. 

[Scot Minesinger]

Short answer:  Even though the A6 you have may be "more efficient", I would go with the original A6. 

It is not really more efficient as Greg points out, it is approx. 20% less capacity due to smaller internal volume, so it is a 20% reduction in capacity on top of an already 20% reduction suffered in going to R134 (Read approx. 40% reduction in total cooling from original A6 w/R12). 

I support r134 on the original A6 (suffering just 20% reduction in capacity, which can be offset by larger factory like condensers) only because r12 is difficult to get and service.  Most shops do not have a recovery machine to deal with R12.  Whereas anyone can add it in (not legally - need EPA card), but few can take it out legally and avoid the $25,000 EPA fine for venting R12 to atmosphere.  Granted this EPA rule does not seem to be enforced strongly for individuals, but it is for businesses.

Given that the more efficient A6 also requires changing the refrigeration fittings which is not always easy or inexpensive, any fuel savings (really is not going to be noticeable), and any "drag" on the engine(which is also not significant unless you plan to race), I would go with the original A6 compressor as Greg suggests. 

Further, remaining with original A6 will maintain the value of the car, as modifications from original often detract from value.  Everyone says they don't care about value until they decide to sell and often reverse previous modifications to get a good price. 

That is a very cool Cadillac - Enjoy!

["Cadillac Kid" Greg Surfas 15364]

David,
At full load, the A-6 compressor only requires a little over 2 HP. You would be going to a lot of effort and expense, and I do not believe you would notice a difference in, say gas mileage or engine performance.
Greg Surfas

[Dan LeBlanc]

Further, remaining with original A6 will maintain the value of the car, as modifications from original often detract from value.  Everyone says they don't care about value until they decide to sell and often reverse previous modifications to get a good price. 

A6 compressors debuted in 1962 

Cadillac used the A5 compressor until the end of the 1961 model year.

[Scot Minesinger]

Right A6 was in 1962, but still I would go with the original compressor A5, rather than one marketed as a replacement that is more efficient due to reduction in capacity and difficulty in the refrigeration line fitting compatibility.

[35-709]

I have been told that GM offered an upgrade kit back in the day to convert from an A5 to an A6 after the A6 was introduced, so it could well be that a Cadillac older than a '62 would have an A6.

[David Greenburg]

Thanks, everyone.  I think I will go with a regular A-6 since my car is already plumbed for it, and it seemed to work well during the brief time I had it before it failed.

[Dan LeBlanc]

The A-6 is a bit of an upgrade over the A-5.  Just as the name implies, the A-6 is a six cylinder compressor, and the A-5 is a five cylinder.  Sticking with one is a good idea - these compressors were used on just about anything GM (and some competitive marques also) well into the 1980's so replacement units and/or parts will be available for quite some time.  Parts are becoming scarce for an A-5 unit and not many shops will touch them anymore if you're in need of a rebuild.