The situation is as follows:
I had the system charged with “Freeze 12” in late August 2006 and it functioned OK but not as cold as it should have been. When the car was brought out for the 2007 season, it didn’t blow cold at all. Fast forward – the car was taken apart for resto in 2008 and I’m now finalizing putting it back together. The compressor, condenser, dryer and lines are off. I know for sure I need a new dryer, the condenser liquid line (it snapped coming off) and the muffler and hose assembly (the hoses are attached with a worm gear clamp).

Should I now “just” attach it back with the new parts and go to an A/C specialist and “see if it works? Should it be retrofitted for 134a? Is there an “upgraded” compressor and/or condenser I should put on (that would fit existing lines) before I bring it somewhere for the charge? What about the POA valve?

I’m not bringing it to the place that did the recharge in 2006 because I don’t think they are really “technical” on Air Conditioning. When I mentioned to them back in 2007 that the charge held for only a few months, he blamed it on me because of the worm gear clamps saying they “probably” caused the leak - but he didn’t give me any input before he did the recharge saying the setup was faulty.

Any comment appreciated – thanks.

 

Are you doing a straight restoration or are you modding parts?

 

You're not supposed to have worm gear clamps. If it were mine, I'd replace all the hoses, every o-ring, receiver/drier or if you have a VIR, all its seals and the desiccant bag and lastly the compressor. Compressor can leak at the front seal and the rear where the four bolts are.
The parts are not that expensive and if you don't replace all of them, you'll be chasing down leaks forever. Those old porous hoses and seals have to go no matter what.

Even with the best electronic detectors it can be a ##### to find all the tiny leaks in a car that old...and believe me, you most likely have multiple leaks that all add up. Dyes work well but only after it leaks down again and the angry owner brings it back. If I was in the business I wouldn't give more than a 30 day warranty on any car over 5 years old.

Changing to 134A is a good idea since everything is out and you're starting fresh. You'll need a correct metering device and modify the system charge. Imo, the replacement R12 products are not much better than 134A and you won't be running to Walmart to pick up a cheap can.
Personally I stay with original R12 in all my old vehicles because I like getting the cabin so cold on a 100+ degree day that the windows sweat on the outside. My new vehicles are good but not that good. That and I have access to R12.

 

Depends on how much you want to spend and what you want in the end.

At the low end of the cost spectrum the answer would be (and what I would do) is put R12 back in it and go like original. The reasons are: R12 isn't that expensive anymore because nobody uses it; Your system is designed for R12 (there isn't and NEVER WAS and still isn't such a thing as a drop in refrigerant, and 134a uses different pressures and heat exchange temps than R12 so it won't perform as well); You won't have a costly retrofit; It'll look stock and work like stock.

But here is what you should consider doing if you go that route to ensure the refrigerant STAYS in your car: First take the hoses to an air conditioning place and have them replace the rubber with new 'barrier' hose. It's a lot less permeable than your stuff. He'll keep the ends the same and replace the hose with new hose. Make sure to tell him to be VERY CERTAIN he puts the hose ends back on the SAME ORIENTATION as you gave him. That won't cost you very much. Or, just buy a new hose. But get away from the hose clamped ends if you can, particuarly if you go to 134a.

Then, I'd probably have the compressor disassembled and rebuilt, or you can do it yourself if you're handy and have some tools. You can get all the replacement parts at: http://www.centuryautoair.com. I've bought lots of parts from him and rebuild a number of compressors. Easy to do. The front seals in them typically leak and that's probably where yours leaked out. It's the most common leak point on a system. The oil that's in yours is for certain contaminated by the hybrid refrigeration you used before. Drain it and install new when you're done. Be sure you get neoprene seals which are better than the old style rubber. Or, you can just buy a rebuilt compressor. It should be rebuilt with neoprene seals anyway. Also install a new dryer and other new parts like you planned.

Then, when you hve it back together but before you go to charge it up, if you REALLY want to see how good it is, charge it with Helium for a week, say 100 psi. Helium has the same atomic weight as helium (the smallest atom) and if it holds the Helium for a week or two, it'll never leak refrigerant unless disturbed. Chances are you'll skip that step, but then take it to a refrigeration place. Maybe a good refrigeration outfit will have a tank of Helium and do that although most don't. They typically use nitrogen and it's a lot larger molecular size.


The other approach is to change it over to 134A. If you plan to buy a new compressor anyway, then this probably makes sense. Just besure to buy a new condenser too for 134a because you need greater heat transfer than the r12 system has. And they make Harrison style compressors that look a lot like yours and will mount in place of your compressor. These are a modern compressor. Amazon.com is a good place to find a new replacement compressor. I'd probably have a good auto air conditioining place do the final refrigeration work. Be sure to find a place that isn't a fly by night outfit. They'll have good experience for you and can work with you.

Good luck!

 

After weeks of thought I can tell you what I'm doing. I am redoing it all. Got a new drier, filter, replaced the hose behind the compressor, got a rebuilt to r134 spec compressor. My condenser and evaporator look pretty good, so I did not replace those.

You also need to replace the schrader valves. Available at any auto parts store.

I did replace the fan, and a bunch of other parts not directly related to the A/C but to the heat and A/C system in general.

I have one of those small vacuum pumps from Northern Tool and plan to pump the system and then charge it with one can of leak detect R134.

Hopefully this will reveal any leaks.

If all is ok I'll recharge it. It takes slightly less refrigerant.

 

Hey . I will review all your 3
comments and appreciate you taking time to post them
thanks, Fred

ps.. trying to getterdone

 

OK, so just for the heck of it, I went to my "local guy" this morning and said "when I put the a/c back in my '69, should I go with R12 or retrofit for 134A?" He said that without a doubt, go with 134A cause he can't get R12. He said that he only has a couple of cans of R12 and he said it was just enough for "topping up" which wouldn't be my situation. I plan to give Century Air a call.

 

Yeah, that sounds good, going to 134A, but just remember to change all your hoses, o-rings and the front condenser too. Do your best to flush out the oil in the evaporator THOROUGHLY. Seriously. Do an extra good job. If you don't replace the condenser with a 134 unit, you just won't have very cold air on hot days. Read up on it and you'll see. There is a product called Nylog which is a thick goo for sealing up joints too. May want to look into it. And by the way, it's simply NOT TRUE that you can't get R12 anymore. There is lots of it out there. It's all over Ebay, just look. There are always guys selling it at car shows for $5-8 a can. Your dude is giving you a line, or at least he isn't able to buiy 'NEW' R12 through his USUAL vendors and doesn't want to step outside the box. I bet if he called up Hudson Technologies he could buy a $100 lb cylinder if he wanted to. Of course it would cost him plenty. They just don't make it anymore, and they haven't made R12 consuming items in quite a while (reduced the demand) not that you can't buy it. In Europe they have quit using 134a in cars. R22 is being phased out this year. Who knows when 134A is going to be phased out?? Either way, it's out there.

Another good reason to stick with R134a is Ozone depeletion. The facts are facts: you open up a can or R12 and it WILL get to the ozone someday. It floats around for 19 years until it gets there and destroys Ozone. It's all chemistry ...that's why they didn't take that long to outlaw it once the science got out. I'm not here to spill green, but the science it out there and something to consider.

You might want to just buy a rebuilt compressor unless you're intrigued and want to re-seal a compressor, and keep your original. Chances are high yours is just fine other than the seals. You'll probably need to buy a seal installing tool. Frankly I like to 'explore' rebuilding as many areas of a car as possible. I was rebuilding automatic transmissions when I was in high school. Ya learn a lot. Amazingly I hadn't pulled apart an a/c compressor ever until last year (wife's jeep). I think that was the only part of a car I'd never rebuilt. It was fun. Good luck!

 

It is definitely a good idea to convert to R134. There is plenty of info on the web on how to do this. You may want to start here:

http://www.corvetteforum.net/c3/zwed...c/retrofit.htm

Remember to not overfill with Ester oil, and to not overfill with R134. Too much will not be as efficient. Also, the condenser will work just fine while the car is moving. It is only when stopped that it tends to not be as efficient. If this becomes a problem, you may want to add a fan.

 

Re-did my 77 with all new parts with the exception of the evaporator assy it is used, the orginal one was bad. Put 134 in it and it works like a champ.

 

I meant to drop this link into my earlier email:
http://dkshamli.wordpress.com/2009/1...-aftereffects/

 

Thanks for the link

 

Thanks - Yea, he really isn't an "AC" shop. I got a couple of "links" to AC forums from the folks at Century Air that I'm going to look at