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Old School advice

75sled on Fri October 31, 2008 12:01 PM User is offlineView users profile

Year: 1975
Make: Cadillac
Model: DeVille
Engine Size: 500 ci
Refrigerant Type: r12

Hey guys, I need some advice here. My compressor and now my clutch have locked up on my 75 DeVille. My mechanic has given me a decent price on redoing the system, but he recommends highly to remove the VIR assembly and install other "stuff" to replace it. This will intern make the compressor cycle off and on instead of running constantly like it did when it was new. I don't have a problem with this, but I sorta wanted to do this myself, and i don't know exactly what he wants to do nor where to start.

He says, emphatically, that if the VIR wasn't leaking now, it would soon be leaking and then I would have to do something anyway. I have read up a little on these old systems and those who like them, LOVE them, those who don't, hate them. Seems to be no in between. So am not sure exactly what to do. I need to do something because the car isn't driveable like it is, due to the AC belt being the same as the power steering belt....try driving this beast without power steering.

Since I am not completely knowledgeable, on AC systems, I am not sure exactly where to go with this.

Edited: Fri October 31, 2008 at 12:04 PM by 75sled

mk378 on Fri October 31, 2008 1:47 PM User is offline

You should keep it stock. Those cycling adapters don't cool as well and they wear out your compressor clutch. The valves sometimes quit working but I haven't seen many people here talk about them leaking. Servicing procedures are somewhat different though. The main reason for trying to sell a conversion may be that your mechanic is not wanting to try to deal with something he doesn't know.

The only problem you may have is that the pulley bearing has seized. If that's the case, it can be replaced without changing the whole compressor, though there could be compressor seal damage from the bearing overheating. Can you turn the inner shaft and front plate of the compressor? Those drive the actual compressor mechanism.

75sled on Fri October 31, 2008 2:02 PM User is offlineView users profile

No it won't turn. Besides it was already determined that the seals on the rear of the compressor were shot. He tried to charge it for me and he said it was blowing out the rear as fast as he could pump it. Course it didn't take much to figure it out.

So if I keep the original system in tact, and replace the compressor, what else do I need to replace. I found a reman compressor on for $131. I can definitely swing that. And if I can identify the other items that you may suggest and find them on that site as well, i may be ready to do this. Also, is there a DIY way to check this system for leaks? the car doesn't have many miles on it, but it did sit in a barn for quite sometime. I have been driving it daily for about a year now. So I figure fixing the AC will just make it that much more pleasant to drive.

JACK ADAMS on Fri October 31, 2008 3:49 PM User is offline

Well I would have to agree with the other post, stay with the old VIR and replace the compressor with New if all possible and you can read or Flushing and Compressor Warranty policies for more information. Do to the clutch ware and cycling this will be your best option. Hope this helps and good luck…

75sled on Fri October 31, 2008 4:59 PM User is offlineView users profile

I sent a message to a "Jack" at on what the warranty states to replace. I was under the impression that the VIR was in place of some or all of the items that requires me to change to instate the one year warranty. Am i wrong in my way of thinking? If so, where do I find these parts, as ACKits didn't list them for my car?

BTW, is there a step by step somewhere in this forum for a car as old as this?

JACK ADAMS on Fri October 31, 2008 7:41 PM User is offline

We can get all the parts for you that you will need to do the jog correctly. Just give us a call Monday and we will get quote together for you. Have a good week end……

JJM on Fri October 31, 2008 9:01 PM User is offline

The A6 compressor shaft seal will leak sooner and more than a VIR ever will. Does that mean you should remove the A6 too and install other "stuff" to replace it?

Why do some hate VIR (and POA and STV) systems? Let me try to put the delicately: THEY'RE IDIOTS! Since they don't understand how to diagnose, service, and repair these exceptional systems, their solution is to rip them out altogether and replace them with what they do know, which is a dumb switch that clacks the compressor on and off. Clack on, clack off, clack on, clack off... yeah that'll improve cooling efficiency and promote longevity. Brilliant.

I think the fact that this system was functional for 33 years is a testament to how well it was engineered.

You've got a wonderful Cadillac, the last of an era of big, powerful vehicles GM was great at building, and what America was all about. Compare that 5,000 pound DeVille to those stupid Prius and Smart ForTwo pieces of junk. Please don't wreck that wonderful classic, keep it VIR (technically it's EEVIR in '75 and '76) and R-12 and you won't have any regrets.

I love that 500 V-8. Is yours EFI or carburetor?

If you're willing to invest in the A/C tools to do the job - all of which are available from the sponsor of this site - you can easily do this job yourself, save yourself lots of money, and have the tools for future repairs on this and your other vehicles. Unlike your "mechanic" these systems are not a mystery to us, and we're here to help.


When considering your next auto A/C purchase, please consider the site that supports you:

TRB on Fri October 31, 2008 9:08 PM User is offlineView users profile

Originally posted by: JACK ADAMS
We can get all the parts for you that you will need to do the jog correctly.

Jogging must one of Jack's side gigs. But if you need help with the A/C we should be able to help with that also. Jack and I are heading to SEMA next week so if you don;t get a hold of us this Monday we will be back the next.

I also agree with what Joe has just mentioned. These things will run for a long time and would just replace what is needed.

When considering your next auto A/C purchase, please consider the site that supports you:

Dougflas on Sat November 01, 2008 10:17 PM User is offline

I also say stay with the OEM system. The ATC system on these Caddys were fanatstic. Make sure you buy a VIR desicant kit.

75sled on Mon November 03, 2008 10:07 AM User is offlineView users profile

Yeah i found the desicant kit at Rock Auto. They also have an expansion valve but in the description it says, "Rear Unit". Does that mean it is for like a Limo with a rear A/C or what.

I couldn't find anything other than the compressor at ACKits, and I intend to buy my compressor there, but what about the other stuff? Can I get everything there?

My plan is to buy

desicant kit
o-ring kit (I assume these are for the line connections)
Nylog Thread sealant

Is there anything else I would need to replace, or is any of this stuff listed not necessary?

75sled on Mon November 03, 2008 10:11 AM User is offlineView users profile

BTW JJM, mine is carburated. I love it. It has been un usable for about 5 weeks now, and it is killing me not to drive it. I did ride it down the road this weekend, and even without the power steering, it was fun. But instead of taking an acre to turn it around it took an acre and a half

dasinc on Tue November 04, 2008 1:24 PM User is offlineView users profile

The expansion valve is in the VIR. VIR stands for "Valves In Receiver". They are replaceable as is the suction throttling valve that is also in there. You can also get rebuilt VIR assemblies as well. Do you need to change it? I guess I would see how the oil looks that is in the VIR or compressor. A6 compressors usually don't put alot of debris in the system when they lock up.

Take care,


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