Pro6TEN compressor install on 1974 CdV with 472

[TJ Hopland]

Secondly, any air that enters the system while under vacuum contains moisture, and with the lows of Psychrometrics (the study of the properties of an air/vapor mixture), there is an enormous vapor pressure differential allowing a great deal of moisture to enter

So it sounds like its a less than ideal design to have a seal in an AC system that doesn't really work under vacuum?   I don't remember how fast mine lost vacuum,  I'm thinking it was noticeable drop within a half hour. 

Other than that seal quirk it seemed like a decent unit.  Having that fitting swivel made it into a fairly universal fit part rather than having fully custom units for every few degrees of different angles required or different nipple elbow sort of bits that I think is also a common method for aftermarket parts like this.

["Cadillac Kid" Greg Surfas 15364]

TJ
vacuum leaks can occur ANYWHERE there are tubing or piping connections as well as the compressor shaft seal. Vacuum IS NOT THE CRITERIA USED TO DETERMINE WHETHER AS SYSTEM IS LEAK FREE. The system operates under pressure . The shaft seal operates under high side pressure and sealing against pressure leaks is what is required.
Greg Surfas

[Chad Speer]

I'm going to call this project done.  After pressurizing the system with nitrogen I was able to use a soap solution to identify a missing o-ring at the eliminator block.  That was a fairly significant leak.  I then noticed it was leaking down maybe a few psi per day, so I took my time looking for anything else.  I finally found a slight leak in the hose from the compressor to the condenser.  That hose seems difficult to source, so I slapped on some black Monster tape to see if it'll hold.  In the end, it was holding pressure overnight, and then held a vacuum around 500 microns for a few hours.  I think that'll be good enough unless the hose gets worse.

I did have trouble getting the belt tensioned.  The previous owner had used a NAPA Premium XL 25-9600, and I ran out of adjustment at the power steering pump.  I then tried a Gates XL 9590, but I couldn't get that one over the pulleys.  I finally had luck with a Gates XL 9600, so maybe the original belt was just stretched a bit.  I made the tool from the Cadillac Shop Manual to apply the tension, and it took quite a bit of force to get the belt tight enough to not slip when turning the steering wheel with the compressor clutch engaged.  She's taut!

I made the front bracket from a piece of steel angle.  I think it was 1/8" thick, which seems plenty for this setup.  The pulley on the new compressor has a slightly larger diameter with bolt heads around the perimeter, so the upper radiator hose was interfering.  I used a 3d printer to make a support for the hose to provide clearance.  I'll probably revise that a bit, but it's doing the job for now.  I have ice cold air and my power steering no longer struggles on occasion at idle.

Thanks for all of your advice.  This was a daunting project for me, but it feels great to have it working!

[TJ Hopland]

I can't tell does this have an HEI or still a points dizzy?  If its points it looks like maybe you could cut a chunk out of the hose to get a little more belt clearance?  If its an HEI then I assume its already jammed tight into the cap.

And this started out as a single or dual belt with a smog pump?  Looks like you have one of the aftermarket pulley sets to get rid of the smog pulley issue? 

And refresh my memory what is the selling point of this compressor?  OE lines plug into it but the bracket and a few other thing is different?

[Chad Speer]

I have an HEI distributor and no smog pump, so a single belt on both the old and new compressor.  I don't know if that was the original configuration.  The VIR eliminator (installed by the previous owner) causes the compressor to cycle frequently.  Apparently, the A6 doesn't like that.  I can't say for sure what caused my failure, but I decided to go with the modern compressor design as a precaution.  The front bracket modification is no big deal for someone who is comfortable working with metal.  I'm on the front end of that learning curve, so it was a challenge for me.  The rear bracket is unmodified, with just a couple of washers to move the compressor forward a bit for pulley alignment.

[TJ Hopland]

How close is the hose from the belt?  It looks real close in the pic?

Don't be surprised if you have to go re tension the belt a time or three. For some reason modern V belts sold for automotive applications seem to do a lot of stretching and seating at first.

Fingers crossed for you that the rest of your climate control system keeps working.  When I fixed the AC in my 73 after owning it for almost 20 year of it not working I first tested to make sure all the controls were working and they were.  That lasted about 2 months before I was buying Tim's troubleshooting manual to find out my amplifier and transducer had failed.  Guess they liked only occasionally provide some heat in the spring and fall, when I asked them to work in the summer too they just said we are outta here. 

[Seville Life]

There's a lot to read in this thread. I just want to get a few things clear.

Cadillac moved to a single belt A6 to accommodate being able to order HEI in the 1974 model year. Actually the change took place if my memory serves me right in mid-1973. It's described in The Serviceman.

I am and always have been lost as to why you insist on using R134a which simply, technically does not work properly in our R12 systems. The key here, and this has been a huge border-line legal issue re old Rolls-Royces, is the use of PAG oil in the A6? DO NOT USE IT. Simple.

The A6 compressor is designed to run on 525 grade mineral oil. Obviously this doesn't work with R134a gas? It is all designed to fail. The correct mineral oil will though work with RS24 gas but I'm not sure if you guys can buy it in the States? We are at the mercy of the tree-huggers today.

If you can buy it you'd do well to, sadly it appears in Europe to be very expensive. If though you use it with 525 mineral oil it works superbly AND without trouble. Bought my '78 Seville in '05, the compressor was missing. Found a second hand one on a wreck. Removed it, drained its oil as Cadillac told me to. Refilled with new 525 mineral oil as per the book then vacuumed down the system as per the book. We waited 1 hour, no change. When the cars are being assembled they are vacuum held for no more than 10/15 minutes. Then we charged it with RS24 and leak tested it. All good.

It lasted 17 years without problem? I drive my car most of the time. I've just completed a 14 month road trip across Britain and Europe. Doing it right is the ONLY way to succeed. Paul

[The Tassie Devil(le)]

There's a lot to read in this thread. I just want to get a few things clear.

I am and always have been lost as to why you insist on using R134a which simply, technically does not work properly in our R12 systems. ....... Paul 

G'day Paul,

Well, If one only has access to R134a, then one has to use it.

The new car manufacturers don't really care about the old car industry, and as things change, we have to change and adapt.

My '72 Eldo is running good with R134a, but then, I don't have the Arizona heat down here.  But, I do know that when it was recharged, I am pretty sure the put in a bit more of the R134a than was normal.  This was in Connecticut in 2008 before I brought the car home.

Bruce.

PS.   Selling R12 is illegal in most places on this earth.   And has been for a long time.   Don't know what the penalties are, but down here, it is high.

[TJ Hopland]

In the USA R-12 availability especially shops that still have equipment and are willing is pretty hit and miss, mostly miss.  I'm in an area of 3.5 million people and only know of one shop.  I would guess there is more but they seem to be smaller shops that are much harder to find. I'm not even sure about the classic car shops and the extra problem with them at least in my area is 9 out of 10 seem to have a terrible reputation like so bad you don't know how they can still be in business and that 1 good shop is booked several years out for new customers. 

The one shop I knew of (where I bought most of the parts for my project) said that counterfeit R12 is still a huge problem.  Back when they first quit making it and prices went nuts the counterfeit people apparently jumped in big time so now there is 30 year NOS counterfeit product out there so that's one more factor driving up costs for the shops and a risk if you are going to buy it yourself.  The people you are buying it from may have horded it back in the day and never used it so don't know its no good.   

[Chad Speer]

Paul, you may well be right about just leaving R-12 in the system, but that was not an option in my case.  The system had already been converted.  Fortunately, I was very satisfied with the cooling performance with R-134A.

I don't know how availability of these refrigerants varies around the world, but it can be a challenge in the states.  I bought a Midea window unit last year that uses R32.  At the time, it looked like R32 was not available anywhere in the US.  I modified that unit to use as a split system on my motor coach.  Since that lengthened the line set considerably, I needed additional refrigerant.  I had to convert the unit to R-410A since R32 was not available.  I also lost some cooling capacity in doing that, but it is inconsequencial in this case.

[Chad Speer]

How close is the hose from the belt?  It looks real close in the pic?

TJ, the hose crosses over the belt at a 90 degree angle, so anything beyond that point in the photo is an illusion.  Where it gets close is the bolts on the outer diameter of the pulley.  Those clear the hose by about 1/4 inch as they spin.  The bracket supporting the hose extends over those bolts, so it's actually okay, but it's closer than it needs to be.  I have a new hose on hand that seems to have a slightly different shape than the old hose, so when I replace it I'll make a new bracket to maximize that clearance.