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Newbie Question on Vehicle Restoration

BearGFR on Sat April 17, 2010 2:21 AM User is offline

Year: 1969
Make: Pontiac
Model: GTO
Engine Size: "400"
Refrigerant Type: R12
Country of Origin: United States

Howdy,

Hoping someone can give me some direction here. About 20 years ago (no kidding) I started restoring my 69 Pontiac GTO. Not knowing any better, I disconnected all the connections to the various A/C components and didn't cover them. So, for the last 20 years or so, everything has pretty much been open to the atmosphere. Some time back I heard this might be a bad thing. Is that right? Are all my components now junk or is there a way to check them out to find out. Everything was working fine --- 20 years ago.

Thanks much,
Rob

HECAT on Sat April 17, 2010 5:56 AM User is offline

I would say if the compressor had not been turned some to distribute lubricant, there may be internal rust (humid climate?) formed on the steel parts and the shaft seal is surely done. I would not risk the compressor failing and contaminating everything, especially after a good effort to restore.

Depending on the materials and type of construction; the condenser and evaporator may be cleaned of old mineral oils (maybe tar now) and spiders. Try a mineral spirit fill, soak, drain, and blow into a clean bucket to evaluate; if in doubt, toss it out.

There is not much else I would want to reuse; replace the hoses, OT, accumulator, etc.

If this is not a "factory" restore; a modern 134a compressor and parallel flow condenser would be an option.

-------------------------



HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 


Edited: Sat April 17, 2010 at 5:57 AM by HECAT

BearGFR on Sat April 17, 2010 10:07 AM User is offline

Thanks Hecat,

That's encouraging to hear. I'd like to avoid replacing the whole system if I can. Will any of the components work at all with newer refrigerant? Is there a way to check the compressor for internal rust? Can the shaft seal be replaced?

All the parts have been here in Texas --- Dallas for all practical purposes --- since disassembly. It's more humid than where I grew up, not as bad as other places. Maybe there was enough oil in the system when I took it apart to leave a coating on everything sufficient to inhibit rust, if I'm very lucky.

The car isn't going to see daily use. It's strictly for fun: cruising, a little racing, maybe a road trip once in a blue moon.

Thanks again,
Rob

HECAT on Sat April 17, 2010 11:44 AM User is offline

"That's encouraging to hear. I'd like to avoid replacing the whole system if I can."

...That is possible, but I think you should be replacing most of it.

"Will any of the components work at all with newer refrigerant?"

...Good news, the evaporator can; if it can be cleaned, if it is not corroded, or a leaker, etc. You can use the condenser you have (provided it is properly cleaned and leak checked) if you are going back with R-12; and you should upgrade to a Parallel Flow Condenser (PFC) if using R-134a.

"Is there a way to check the compressor for internal rust?"

...Take it apart.

"Can the shaft seal be replaced?"

...Yes. IMHO, I would not want to use or trust the old compressor, even if it looked clean inside. There have been so many upgrades and performance improvements made to the replacement compressor options you have. If the old one is used and fails, it will contaminate you newly cleaned system (i.e. more work, more dollars, etc.).

"The car isn't going to see daily use. It's strictly for fun: cruising, a little racing, maybe a road trip once in a blue moon."

The A/C doesn't care if it's a daily driver or a race car.

-------------------------



HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

bohica2xo on Sun April 18, 2010 2:07 PM User is offline

A '69 should be a TXV/POA system.

Hopefully the POA is still ok. Bench testing it would be my first step.

The TXV is easy enough to replace, and not very expensive.

The hoses can & should be rebuilt. The site sponsor can rebuild the OEM hoses for you if you ship them to him.

A new receiver is needed, and available.

The condensor is a fin & tube unit, and probably can be flushed. The evaporator is the hard part to flush, and it needs to be spotless inside.

For a points car, the evaporator could be replaced and it is unlikely anybody would spot it.

The compressor is an A6. The original to the car compressor can probably be rebuilt - as long as it did not spend 20 years open in a florida backyard...

Plenty of work, but not impossible. You should keep the TXV / POA system & the A6. I would stay with r12. A '69 goat gains value every year, and every time Foose ghetto's another one up your OEM unit is worth more.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

BearGFR on Sun April 18, 2010 2:34 PM User is offline

Ok.... I can build engines but A/C terminology just makes this cool "whooshing" sound as it flies over my head.

What's a TXV and a POA, and how do I bench test? (Pointing me to a link or another post to learn this stuff is ok. I can read - sort of

Thanks!
Rob

Hoping my POA isn't a POS

bohica2xo on Mon April 19, 2010 1:54 AM User is offline

Bear:

This is a POA valve:




This NOT what you want to see inside:



Here is one of the threads about testing a POA, there are several on this site:

http://www.autoacforum.com/messageview.cfm?catid=20&threadid=7567


The TXV is the thermostatic expansion valve. Like THIS ONE available from the site sponsor.


The POA has been out of production for decades. NOS parts are hard to find, and "rebuilt" can be of varying quality. It is a precision pressure regulator for the evaporator core.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

NickD on Mon April 19, 2010 3:53 AM User is offline

In 69, believe GM replaced the POA with the STV, kind of similar in function, suppose to feed the TXV with a near constant 28.5 psi of pressure, was a great system. Compressor ran all the time, but the load on the engine was proportional to the cooling needs.

A6 had a great ceramic compressor seal, worse was wear on the shaft that could cause leaks, a gauge can be jury rigged to the outlet and the compressor hand turned to see if you can hit and hold 100 psi. Mineral oil was pretty good for protection, but questionable about getting a good check valve seal.

Where my memory is hazy as to when GM switched from brass to aluminum for the evaporator and condenser, brass can be cleaned with acid, aluminum cannot. You can certainly look at them and tell what they are made of.

Certainly you have a shop manual for your car, AC description was pretty good in these manuals and could be purchased directly from GM for four bucks back then including postage. At your library, may have a copy of Professional Motors for your 69 and other vehicles. Also has a fair description.

Not sure about your climate control, was driving Caddies and Buicks back then with automatic temperature control, could set the entire unit on the same workbench I have today with a vacuum pump and a 12 volt power supply and watch everything work. Cars are long gone, plus the manuals, but the workbench is still here, with a new Formica top on it.

Chick teases about using a compressor for a boat anchor, A6 would work for that, even for the Queen Mary. Todays compressors would be more suitable to hang on your key chain.

BearGFR on Mon April 19, 2010 3:06 PM User is offline

No climate control on the GTO, you have to alter the settings by hand to maintain the temp you want (the horror!).

Many thanks to everyone for all the help, you've given me a starting point and that's what I needed. I'm building this car for me to enjoy and eventually to pass on to my son. Resale value is of secondary concern behind that. It will have the original numbers-matching block, although the bits inside that block are going to be somewhat --- "improved" On pump gas, it ought to run mid 11's.

I'm going to upgrade the handling and brakes also, but for the most part it's going to appear stock - to the casual observer at least.

Thanks again everyone,
Rob

If you care and want to see a pile of photos on the project, go here:

Rob's 69 GTO Project

bohica2xo on Mon April 19, 2010 7:24 PM User is offline

Well, you certainly (cough!) have enough of that goat apart to make A/C service easy... LOL

Quite a project. Getting the A/C back together will not be that hard for you. It looks like you have the skills to do the work, just lack the terminology, and a few special tools.

I believe that by '69 pontiac was using aluminum evaporators. The STV valve did the same job as the POA valve, but it was adjusted differently. I honestly can't recall when that change over from STV to POA happened, but one member here (Douglas are you reading?) will likely remember the month & week it happened.

Nice work.

B.



-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

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