'66 Cadillac AC help

[Ralph Messina CLC 4937]

I hoping for advice.

I just got a ’66 convertible with non functioning AC. Two owners previous changed the system to 134 and now the compressor is frozen. Being old school stubborn, I want to return it to FR12 which will a require a rebuilt old style “C6..?” compressor. I know how to do all the mechanical tear down and build up. My question is about the rest of the system. What’s the best way to clean and test the evaporator and condenser. Is a good radiator shop boil and pressure test followed by an alcohol flush acceptable? I plan on replacing the dryer and using new oil and possibly the hoses depending on condition. 

Any help is appreciated,

Ralph

["Cadillac Kid" Greg Surfas 15364]

Ralph,
With a system of unknown chemical composition (what oil, refrigerant, etc. have been previously used?) if it was mine I would completely disassemble the components, disconnect all hoses, and thoroughly flush everything with an appropriate material, such as Flush R-11 for which you need an refrigeration license.  Both the P.O.A Valve and the expansion valve need to be checked, and cleaned thoroughly. Be careful with the TX Valve, and if there is any doubt, replace it.  The system needs to be recharged with refrigerant oil (I personally prefer Ester oil) in accordance with the distribution (the amount of oil replaced in each component) indicated in the service manual.  A new dryer, and a (new or) rebuilt A-6 compressor (AC Delco still does a good job of rebuilding them), re assemble with new O rings, evacuate to 28 inches for 1 hour, and then recharge.  I hope you intend to use R-12, because if that FR-12 you wrote is "Freeze-12" I would strongly advise against it. You have just spent 10 to 12 hours cleaning up your system, and you don't want to screw it up with a non approved and chemically essentially unknown attempt at replacement.  R-12 is still very much available.
Greg Surfas

[Ralph Messina CLC 4937]

Greg,

Thanks for your reply…..very helpful. I’ve never heard of the flush. My experience with Freon compounds is that once they evaporate â€"leak out â€" they leave no residue. I would have thought any solvent degreaser would clean the old oil out of the system.  You now make me wonder whether I wouldn’t be better off replacing all the components and be done with possible problems. I don’t know what was done to the system or the quality of parts or workmanship. I’ve dealt with “OPR’s” â€" other people’s repairs, and often end up replace everything one piece at a time.

Regarding Freeze 12, I’ve used it for 6 Years in my Brougham with great results. The only issues I had were two dried out Schrader valves that had slow leaks. Once I located the leaks and replaced them the system holds pressure and gets really cold.

Thanks,
Ralph

["Cadillac Kid" Greg Surfas 15364]

Ralph,
One of the greatest hazards about changing an R-12 system to R-134a lies in not removing virtually all the Mineral oil from the R-12 system.  When exposed to R-134a Mineral oil forms a gelatenous goo that plugs up the components.  This goo CAN be removed, but requires a specialty cleaner as previously mentioned to chemically desolve the goo and flush it out of the components. 
I find it curious as to why someone will spend tens of thousands of dollars to acheive originality with an automobile, but skimp on a component that typically will cost about the same as a full tank of gasoling.
Seems like you have a direction in mind. Let us know how it turns out.
Greg Surfas

[Ralph Messina CLC 4937]

I’ve discovered that when this car’s system was converted to 134, all the components were replaced. I will therefore keep it as 134 refrigerant and just replace the frozen compressor. I’m certain that like most replacement parts, not all compressors are created equal. Can anyone suggest a brand and source I should be looking for, or any I should shy away from?


Thanks,
Ralph

[tbirdtbird]

http://www.sanden.com/

they make/rebuild most of the compressors out there anyway

["Cadillac Kid" Greg Surfas 15364]

Ralph,
The "hot set-up" currently is buying a new A-6 compressor from AC Delco.  They run about $400 (+), but the quality of rebuilts today, due to the wear they encounter on the cores sent in leaves something to be desired.  Another issue is that Manufacturers are getting very strict on warranties, and if there is any evidence that a system was not clean and free of contaminants when their compressor was installed, they are starting to reject warranty claims.  That brings us back to the cleanliness issues discussed previously.  You indicated that the previous owner "replaced everything", but if they did such a great job, what caused the compressor to fail.  An A-6 compressor in a clean and properly operating AC System should be considered good for at least a couple of decades if operated regularly (once a week at least).
At that the normal failure is the compressor seal.
A "locked up" compressor is usually caused by lack of lubricant or continuous cycling of the compressor at high engine speeds.
I would, if this were my car, thoroughly flush all components, clean the TX Valve inlet screen, and replace the dryer/receiver when replacing the compressor.
Done correctly the additional costs associated with this work will pay off by extending the lifetime of the system.
Greg Surfas