My A6 compressor failed catastrophically a few weeks ago. The shaft sheared in the middle of the compressor, sending the clutch forward into the fan. It appears that the damage is limited to the compressor and a dinged fan blade or two, so I'm probably lucky it wasn't worse. I read somewhere (I think on this forum) that this was a "rumored" failure mode. Well, I can confirm! I had been trying to diagnose a periodic rumble that I felt, as much as heard. I had definitely narrowed it down to being present only when the compressor was running, but the air was cold and it didn't seem too violent. I probably should have been more concerned. I suspect that it was a sign that I was low on oil, as I have to add R-134a at the start of each summer, but have not added oil. Anyway, I could use some advice as I try to get her going again.
The previous owner converted to R-134A and installed an Old Air Products VIR Eliminator kit. He also bypassed the superheat switch, which appears to be a common move when installing the Old Air kit. After the failure I ordered the Pro6TEN compressor from Old Air Products, which claims to be a drop-in replacement for the A-6. After receiving it, I saw a couple of problems. One, the distance between the front mounting plate and the rear mounting holes is slightly different than the A-6. I can elongate a couple of holes in the rear mounting bracket to accommodate that. The bigger problem is that Cadillac apparently used a different pulley offset than every other brand, because my A-6 single pulley sits about 3/8" forward of the Pro6TEN pulley. Not quite the drop-in I was expecting, but I don't blame Old Air Products for that. They reached out to the manufacturer for a solution, but said they don't expect a speedy response.
I could try to fabricate new mounting brackets for the Pro6TEN, but that's really beyond my current skills. My thinking is to have the pulley modified, or have a new one machined to create the proper spacing. Before I get quotes for this from a machine shop, I was hoping to get some input from you guys. Am I missing something simpler?
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Are you sure the pulley on the old one hasn't walked forward a bit? If not then do they offer a dual groove version? Maybe the dual groove would give you more options for spacing?
The stock front bracket bolts to the block with vertical bolts doesn't it so not much you can do there?
Is that failure perhaps one of the things that happens from the clutch cycling maybe especially when the charge is low its short cycling and kicking on with higher load due to higher pressures from just recently have run?
Quote from: TJ Hopland on June 23, 2023, 11:39:14 PMAre you sure the pulley on the old one hasn't walked forward a bit? If not then do they offer a dual groove version? Maybe the dual groove would give you more options for spacing?
The stock front bracket bolts to the block with vertical bolts doesn't it so not much you can do there?
Is that failure perhaps one of the things that happens from the clutch cycling maybe especially when the charge is low its short cycling and kicking on with higher load due to higher pressures from just recently have run?
I suspect that you described the failure mode about right, which means a rebuilt A-6 probably didn't make sense. I decided to change compressor design rather than revert to the original VIR configuration, which I have no experience with. I did just look at the pulley on the A-6, and I don't think it could have moved outward. I mispoke when I said the pulley impacted the fan; it was the clutch. I'll try to go back and edit that. The A-6 pulley seems secure, and restrained by a snap ring. I was nervous about removing the pulley on the Pro6TEN because it looked so strange, but those 6 "Frankenstein" bolts around the perimeter come out and there is no spring tension or anything to cause problems. It just slips off.
The guy at Old Air Products mentioned the 2-groove pulley, but I don't even know if they make that anymore. I can't find an example for sale online. I don't know if either groove would align, but it might be easier to remove material from the 2-groove pulley than to add material to (or redesign) the 1-groove pulley. If anyone has a source for the 2-groove pulley, I'd be interested.
I think you could remake both brackets to accommodate the differences, but it would be a project. Notice that I didn't say that *I* could remake them! Thanks for the ideas, TJ. I just installed a shorter belt for the power steering and took her for a spin. At least I'm back on the road for now.
I believe the new aluminum A6 compressor you have is actually a drop in for GM EXCEPT Cadillac.
I bought one of those and I had to move the compressor forward 1/2 inch if memory serves. I modified the front aluminum (rectangular block) bracket pretty heavy I remember. I opened the holes of the rear bracket to allow catching it with original holes in manifold.
My idea with the dual groove if it exists is that maybe the new groove will be further forward so you could then space the compressor back which sound like it would be a lot easier than moving it forward.
If there is enough 'meat' in the front bracket to allow the proper position maybe present that as an option to the machine shop too. It may be easier (& cheaper) to machine the bracket than a pulley.
Who was it Olds and or Buick that also had a dual groove? Maybe snooping around some of their forums or parts sites will turn up something?
It really wasn't major surgery to move it forward. I used a 4" hand grinder to massage the brackets. I wouldn't hesitate to do it again.
Quote from: V63 on June 24, 2023, 12:45:31 AMI believe the new aluminum A6 compressor you have is actually a drop in for GM EXCEPT Cadillac.
I bought one of those and I had to move the compressor forward 1/2 inch if memory serves. I modified the front aluminum (rectangular block) bracket pretty heavy I remember. I opened the holes of the rear bracket to allow catching it with original holes in manifold.
Okay, that gives me a new direction to consider. I think I could use some spacers between the rear bracket and the compressor to move the compressor forward without modifying the rear bracket. This compressor is so much lighter that I don't think using spacers should be a problem with those beefy 3/8"-16 bolts. Then I would just need to modify that front bracket. That might be easier, and would definitely be simpler than modifying the pulley. I found a front bracket on eBay just now, so I went ahead and ordered that so I can play with it. This is no show car, but it's nearly all original and in very nice condition at 58,000 miles. I'd like to retain the ability to return it to unmodified condition in the future.
Quote from: TJ Hopland on June 24, 2023, 09:26:13 AMWho was it Olds and or Buick that also had a dual groove? Maybe snooping around some of their forums or parts sites will turn up something?
Well I can tell you that the 64 Olds with the 394 has a dual belt on the A/C and alternator.
I don't know if it's permitted, but here's a picture of mine.
Rick
FWIW the double belt systems use belts that are narrower with a different pitch than the single belt systems
Greg Surfas
Quote from: "Cadillac Kid" Greg Surfas 15364 on June 24, 2023, 12:28:25 PMFWIW the double belt systems use belts that are narrower with a different pitch than the single belt systems
Greg Surfas
Thanks, Greg. That narrows down my options, but I think it's still manageable. I've read dozens of your posts on the Cadillac air conditioning systems. I've learned a lot from you.
I found an image I have of the aluminum A68A462AE8-531A-4A97-8F85-9E1186A25D3B.jpeg
Just an update on this project from last year. I was able to shape a new front bracket from 1/8" steel angle, and just used spacers between the compressor and the unmodified rear bracket. I'm currently trying to find a leak that's preventing me from holding a vacuum, and I suspect it's the o-rings on the fittings on the back of the compressor. I added a new set of o-rings from Old Air Products when I bought the Pro6TEN, but now I'm thinking I changed all but those two big o-rings last summer. That's what I get for dragging this project out. My driver window shattered not long after my last post, and it took a while to source a NOS window in that green tint. I'll try to post some pictures when I have it all working again. Looking forward to some cool summer driving this year.
Is the receiver (tank thing) the universal type where the center fitting thing can pivot around to different positions? If it that type what ever they used for a seal doesn't seem to work with vacuum. When I did mine several years ago now with one of those kits it would not hold vacuum very well.
I just got frustrated and charged it anyway and I think it went like 3-4 years before needed a slight top off. I sent them a message asking if anyone else had noted that and suggested they add that to the notes for the part but as far as I know they never did.
Chad,
The proper way to leak check ANY refrigeration or AC system is under pressure. All the joints and seals are designed to hold the pressure the system will be under. Under vacuum the O rings are actually pulled away from their sealing surfaces so they can leak. Pressurize the system with either a bid of refrigerant or nitrogen up to about 50 psig and then using a (now relatively in expensive) electronic leak detector or even soap bubbles on each of the joints you can find out exactly where the system is leaking.
Greg Surfas
TJ - that is the design I have. I'd be fine with an occasional top off, but now seems like a good time to try to get leak free. From your description, I may already be good enough.
Greg, thanks for those tips. I've only worked on my own residential and marine/RV systems with brazed joints or flare fittings. I always vacuum a system down below 500 microns, but I hadn't considered the o-ring issue. I'm going to get a nitrogen tank so I can check it under pressure.
I think its a decent design for pressure its just not especially good for vacuum. I don't know where my leak is, its way to slow to detect. Plenty of places it could be leaking over that many years. It was still working when I topped it off I just could hear the compressor cycling when I wasn't expecting it to be.
Greg, how bad would a 'leak' from a seal design like this have to be before it would actually cause issues drawing in outside air during the vac before charging process? Or once the system is vacuumed down does anything that gets sucked in pretty much get sucked back out? So you just don't want to wait too long between turning off the pump and charging?
TJ
2 things. If there is a leak under vacuum you might find it impossible to find it. Take a look at the connections using an o ring and they all have a "shoulder" on the tube that the o ring presses against when under pressure to fully seal the joint.
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.
Greg Surfas
Forgive if it was mentioned already, but it may be worth your while to source a new fan. I'm sure the impact of the clutch to the fan blades was pretty violent and that could be enough to throw your fan out of balance. May be cheap insurance against an early water pump replacement.
Quote from: smokuspollutus on March 05, 2024, 04:22:39 PMForgive if it was mentioned already, but it may be worth your while to source a new fan. I'm sure the impact of the clutch to the fan blades was pretty violent and that could be enough to throw your fan out of balance. May be cheap insurance against an early water pump replacement.
I appreciate you mentioning that. There were just a couple of small dents on the blades, and it seems to run smoothly, but I don't want more trouble down the road. I'll see what's available.
Quote from: "Cadillac Kid" Greg Surfas 15364 on March 05, 2024, 04:10:27 PMSecondly, 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.
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
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!
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?
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.
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.
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
Quote from: Seville Life on April 03, 2024, 01:49:35 AMThere'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. >:D
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.
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.
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.
Quote from: TJ Hopland on April 03, 2024, 12:05:08 AMHow 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.