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1972 De Ville A/C compressor oil capacity, and determining if compressor is stil

Started by pittjazzlibrarian1, July 17, 2018, 10:14:59 PM

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pittjazzlibrarian1

I acquired this vehicle last month, am doing small repairs and attempting to sell it. The engine was replaced about 14 years ago, then the car was barely driven for 6 years before being stored. Apparently the A/C lines were opened and the compressor removed during the rebuild; the A/C has no refrigerant, and the compressor has no oil. Two questions: how do I determine if this compressor is still good? And what is the required volume of oil for the compressor?

Drew

Dan LeBlanc

The compressor capacity is 6oz. 

If the system has been opened up for an unknown amount of time, you'll need to replace the filter/dryer assembly as well.  Rock auto lists them for under $10.

It's also going to be a crap shoot as to what type of oil is in there.  If it's still mineral oil, you're limited to R12.  If they flushed it and added PAG oil, you're limited to R134a.  If it's Ester, you're fine with either.

At the end of the day, it's not going to be a simple add oil and recharge not knowing what's in there.
Dan LeBlanc
1977 Lincoln Continental Town Car

pittjazzlibrarian1

Thank you for your help.

The compressor is dry, absolutely no oil came out of it at all. I am going to replace the filter-dryer anyway, I already purchased one at a local parts store. I'm installing an R-134 conversion kit, as I'm in California, and R-12 is extremely difficult to find, impossible for a backyard mechanic such as myself. I've already purchased PAG 150 and R-134, and can rent the gauge set and vacuum pump from AutoZone.

Given that there was no refrigerant or oil in the system, the operational status of the compressor is suspect. I'll be looking for a location to bench test the compressor later today.

The hoses look very good, apparently they were replaced when the engine was replaced.

What was your source for the information regarding the oil capacity? I've received three different answers (3.4 oz., 2.7 oz., 8 oz.) to that question, one from a Cadillac dealer that claimed to have referenced a forum, and two on another forum. In none of those cases could anyone reference a specific shop manual or table, so their information is not reliable. Even if I can't find a manual, knowing that you have referred to one for the answer will give me greater certainty that it's not a made up answer. I'd rather not burn up a good compressor, nor gum up the entire system, both would be too costly to recover.


Drew

Dan LeBlanc

I just went through all of this with my 70.  The 1970 shop manual lists 6oz for the compressor.  This is standard for all A-6 compressors that are bone dry.

If the compressor is indeed bone dry, you will be best served by adding the oil to the compressor and then letting it sit face down (on the clutch end) for about 20 minutes.  This will wet the front seal for you.  Before you charge the system, you should also turn the compressor over by grabbing the center portion and rotating it about 20 times before actually activating it.  It will move some of the oil around to where it needs to be.  The valves inside will thank you for it.

Even though nothing came out of the compressor, you've still got oil in the system.  There will still be some in the condenser and evaporator if those have not been removed and flushed. 

You'd be better off using Ester oil in the compressor as it will mix with either PAG oil or Mineral oil if you don't know what's in the rest of the system.  If you put that PAG oil in that you purchased and there's still mineral oil in there, you will indeed gum it up.  It'll turn to sludge.
Dan LeBlanc
1977 Lincoln Continental Town Car

pittjazzlibrarian1

Thank you again for your help. I'll return the PAG oil and purchase ester. It's likely, given that the car was never modified for R-134, that the original mineral oil is still throughout the system. I don't wish to go through the trouble of a flush. The idea here is to get the A/C operational with some degree of reliability and endurance, as I'm listing the car for sale as soon as this and the transmission issue have been resolved.

Drew

35-709

IMO you won't get the system "... operational with some degree of reliability and endurance ..." without beginning with a thorough system flush.  On an old system like that that has been open for quite some time there is no way to tell what is in there.  Again, IMO, if you don't do it right, you are wasting your time and money.
 
1972 Cadillac Shop Manuals for your car are readily and cheaply available on eBay but since it seems you are just interested in flipping the car that probably isn't an option for you.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

TJ Hopland

I will second that, you are already this deep why not flush it?   Starting with a clean system is part of reliability and endurance.  You don't know what or how much oil is already in it or what is mixed in with that oil.   Get the good flush that comes in a metal can if you can in CA. It appears fairly toxic so maybe they don't sell it there but if you can get it it really seems to work.  You can see the varnish like stuff come out and when you are done that musty smell is gone which can't be a good thing.   

Based on what I have heard so far I if it was me I think I would just leave the AC not working and leave it for the buyer to decide if they want to leave it R12 or convert to R134.     

StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

pittjazzlibrarian1

The difference in selling price between A/C not working and A/C working is in the vicinity of $1000.

Reliability at this point means that when showing the car, the A/C will work. Endurance means that the buyer won't come back on me in the next 30 days for the A/C failing.

Drew

"Cadillac Kid" Greg Surfas 15364

Andrew,
IF you want ANY kind of "endurance" with this system it has to be done right.  A system with residual mineral oil from the R-12 mixed with R-134a is disaster waiting to happen.  The system has been opened and is dry so it is anyone's guess s to its condition.
At bare minimum a thorough flushing of all the components with an effective flush like RX-11, followed by a comprehensive leak check and then adding oil to the system.  A total of 10 oz of (I would suggest sticking with R-12 to maintain anything like original performance) either Mineral oil or POE oil. This is distributed 5 oz in the compressor, 2 oz in the evaporator 1 oz in the dryer receiver and 2 oz in the condenser.
If this distribution is ignored the system will oil starve on start up damaging the compressor. 
Before I went too far I would cjheck the compressor seal. If the compressor was dry chances are good you will find the seal bad.
All told unless you have the proper equipment and can do the work yourself you will have $5-600 tied up ion the work to do it correctly.
If you are in So. Cal or somewhere around the Central valley up to Sacto. and expect good performance out of the system sticking with R-12 is a must.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

pittjazzlibrarian1

I've disassembled and dismounted the entire system, EXCEPT that I left the evaporator in its housing. I flushed all hoses, the evaporator, and the condenser. I put 6 ounces of PAG 150 in the low port of the compressor. I reassembled the system, retrofitting to R134a, due to the unavailability of R12 in California. I then connected a vacuum pump and evacuated the system for over an hour at 29 inches vacuum. I then charged the system with R134a to a pressure of 45 psi (300 kPa) at the low side port. I've checked all electrical connections under the hood. I reinstalled the drive belts, started the engine and checked for proper drive belt operation.

Placing the controls in the High position with the temperature control at minimum (below 65 degrees), the face vents get no air flow, and the compressor clutch receives no voltage, thus does not engage. I now need suggestions, or direction to a troubleshooting and repair manual, in order to repair the control problem that still remains.

"Cadillac Kid" Greg Surfas 15364

Andrew,
To guess at what your issues would really be a shot in the dark.  I would suggest you get an original or copy of the Cadillac factory service manual.  There is a wealth of information there as to the Air conditioning system and all it's components. The refrigeration system, the fan bower system, the heating system and the control system.  Get the manual and be sure all your components are installed correctly and the wiring and vacuum systems are complete.
If any of these components are not functional the entire system will not operate even haphazardly.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

35-709

1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2