My2nd 69 442

I have rebuilt my Original to the car AC compressor, replaced the dryer and all AC hoses. Now I'm trying to decide on how I want to service the system.
Should I go with R12 or R134.
My 69 442 is an "all original" car in beautiful condition and I want to keep it as original as possible, only thing not original is the HEI distributor.
If I change over to R134, would that be a serious hit on any OCA judging and would the change to R134 do anything to the value of the car.
Thanks to all for any input

MDchanic

R-12.

Works better than R-134, doesn't need any changes to the desiccant, hoses, POA valve, or condenser, and is still readily available.

2¢ deposited...

- Eric

Funkwagon455

Personally, I am a huge proponent of using R12 in my systems originally designed to run R12. There are several reasons for this, aside from the obvious visual R134 adapters under the hood. R12 runs at a lower operating pressure than 134, this translates to less pressure on your system and less pressure exerted on your freshly overhauled compressor. In addition to that, R12 does not have the tendency to be reliant on continuous fwd motion to maintain cabin temperature. With R134, you will feel the temperature rise in traffic or at lights, especially if your traveling in a very hot climate. The A6 compressor is heavy, it will sling oil, but it will work well. R12 is not cheap, and is technically required to have a refrigerant license to purchase. Craigslist is a good option for reasonably priced R12 for casual use. Again, this is only my opinion based on my experiences, best wishes regardless of your decision.

Fun71

I looked into the R134A conversion after I moved to Arizona nearly 20 years ago. An AC expert told me to keep using R12 for the reasons above - the system is designed for R12 so it will cool better with R12 than with R134A; R134A runs higher pressure than R12 so in a hot environment (120+ AZ summer temps) blowing out the front compressor seal is a serious concern (need to install an auxiliary electric fan for R134A to help dissipate heat and keep pressures within tolerable limits). He said to keep using R12 until it was all gone and there was no other option, then consider changing to R134A.

FYI, there is still a large supply of R12 out in the market due to back in the 90s all the shops recommending converting to R134A, so the supply did not get depleted.

Ozzie

(Real) R12 works better, is harder to find, and is more expensive. I'm unsure about the judging and the vehicle's value but "original" would surely be worth something in both cases.

budg

I do commercial hvac for a living. In all honesty if it's still readily available stay with the r12. Less headaches imo. I mean your system doesn't hold much and the only way you lose it is if you have a leak. I would make sure what you are getting is recycled r12 and not a drop in replacement. And buy some extra cuz you never know when it will become scarce.

Junkman

I would like to point out that the "oil slinging", is the nature of the front ceramic seal, which the front shaft rides on a thin layer of oil. If you have a Delco Seal Kit #6599114 (15-210), there is the instruction sheet that says There is a felt wick in the kit that is designed to absorb this oil, and periodically, you should replace the wick when it becomes saturated. Even though there is a GM part number for this wick, I have never been able to find it available from any sources in the past 15 years, except to purchase a complete kit. The kits are readily available on eBay for about $20.00. I have looked for felt of the proper thickness, but haven't found any as of now, however, my wife did pick up a 1 foot square piece of felt at Michaels last week, and if you use 2 layers. I just don't know if the 2 layers is going to work like a single layer of the original felt.
On all my latest air conditioning work where parts have been disassembled, I am using green Viton O rings in place of the old butyl O rings. I found that even the larger compressor front & rear end plate O rings are available today.
I purchase the correct Delco refrigerant oil from Amazon, since that is the only place that I have found that sells it. Don't know if this is NOS that they are selling off, or it is a current production item. I am not a fan of a Universal oil that works with both R13 & R134, since the oil is what lubricates the system, and O rings, along with keeping them soft and pliable when the system isn't in use over the winter. My experience is that most leaks are at the O rings. I have also experienced leakage from old rubber hoses, and those I replace with the new barrier hose. Most times, these leaks are where the hose is clamped to an aluminum barbed fitting.
When it comes to charging the system, I pull a vacuum for 24 t0 48 hours, and then shut down the vacuum pump, and allow the system to "balance". If it holds the vacuum for 24 hours, then I will charge the system with nitrogen and see if it holds the nitrogen charge for an additional 24 hours. If it does, then I evacuate the nitrogen, and fill with R12. Since I am not doing this work commercially, I am in no rush to get the car out of the garage.
One final thing, if you are using the 12 - 14 ounce containers of R12, purchase a side tap, and use it on the can, rather than using the top of the can taps. I have been finding that the seals at the top of the containers are failing when you put the locking ring from the tap onto the top of the cans. Using a side tap you get to use all the R12 that you have paid for.
Doing the air conditioning work isn't difficult, if you follow the instructions in the service manual, and also read up on the subject on the various auto websites. You can learn from others common mistakes, and be successful in this repair. Buying the equipment can be costly, but if you can borrow it, it is rewarding to know that you did this on your own.

Funkwagon455

Good info!

budg

Junkman, personally I would do the nitrogen pressure test first and then the vacuum test . Why evacuate it twice if you dont need to. The usual method in the industry for leak checking is a electronic leak detector , but soap bubbles are good. Pressurize it with nitrogen and use soap bubbles to check all your joints ,seal , etc. Let the pressure overnight and if it doesn't drop you know you are good. Evacuate it with the vacuum pump overnight and you should be ready to charge it. I work on really large systems that hold 2k pounds of refrigerant and usually overnight is good to charge. I use a micron gauge to be sure.
You shouldn't need one for such a small system. Besides, the nitrogen will absorb any moisture in the system because water will just freeze when it gets below 29".

Just some food for thought.

Junkman

Thanks for your input. I learned the old fashioned way back in the early 1960's, when we flushed the systems with compressed air first, and then with Freon. Recovery was a word that hadn't been invented yet! I will try your method next time. thanks again... Junk


PS... I will edit my original post to correct my error.

budg

No problem. Yes the days of cleaning parts with r11 are long gone . I remember buying it in a spray can. Ah the good ole days.

MDchanic

Excellent rundown.

Just one question: Why are you not using the modern green viton O-rings?
I was under the impression that they were more durable - should I be using the old style O-rings on R-12 equipment?

Thanks,

- Eric

Junkman

Just a brain fart... I meant to say that I only use the new green Viton O rings. I was rushing to finish the post, since I had an appointment that I was running late for. My apologies for the error.

MDchanic

Ah. Makes much more sense. Thought I was going crazy.

Thanks.

- Eric

My2nd 69 442

Thanks all for your input.
I will service my compressor with R 12.
When I rebuilt the compressor I also used the green Viton seals and uses a one piece front seal, then had the compressor pressure checked.
Kenneth, I also have lived a very long time(40 yrs) in Arizona(Tucson), so I'm very familiar with the high summer temps.
I'll have to wait a few more weeks before I get the system serviced as I've had major back surgery a few weeks ago and I've only been able to drive my 442 one time and I had a hard time with the clutch. Hope that gets much better cause I don't want to sell it, but it may come to that.
Thanks again folks

442fanatic

If you are going to use this car alot out on the road, where A/C is going to be used. Such as say a Power tour, or if you do some multi night trips to further out car shows. R134 would easily serviced if ya need a quick charge.

R12 hard to find and ya pay ALOT for when you do find it.

I went through the same question when i did my car. Judging wasn't a concern for me, as someday down the road I may make it to a Oldsmobile ralley... But keeping it charged and economically was..

my 2 cents

Junkman

If the system is properly service, a Freon loss isn't something that he will have a worry about. I know of cars that have been operating for over 50 years on the original factory install of Freon. Besides, if he should ever need to add a bit more of Freon, he can always carry a 12 ounce can along with the can tap and gauges in a small pouch. There is probably a better chance of having a water pump or fuel pump failure before a newly rebuilt system is to fail.

Rocketguy

Thanks to everyone; what a great thread.

I recommend R12 as well. It truly produces refrigerator quality A/C under the hottest of conditions. It will actually pour fog out of the vents under some conditions!

I bought an NOS 30lb bottle of R12 at a swap meet last year. It was pricey but I thought it was worth the $450.

One of my R12 cars required a new compressor last year. I wish I'd known the nitrogen trick (and BTW, how to you charge a system with N2?). It held a vacuum for 24 hours so I charged it with 12 and it was great all last year till I tucked it away; I'll find out later this spring if it held. To other forum members, the nitrogen trick only applies with a completely drained system.

The R12 system on a couple of my summer only cars seems to wane, but only over a period of a 4 or 5 years. If this happens to you I recommend just topping it off with a pound or so as needed.

My2nd 69 442

I didn't mention it before, but I will definitely do a system pressure check with nitrogen before vacuum and service.
Any suggestions as to what pressures the system should be checked to.

MDchanic

The CSM says that loss of up to a pound a year is to be considered normal.

Clearly a well-maintained system in god condition should lose less, but these systems were not designed to be as well sealed as newer systems seem to be.

It makes sense to plan for a top-up every few years.

- Eric

Koda

I have a R12 system converted to R134 with original POA valve and such. It cools adequately, but it is reduced from R12 performance. I will convert it back, someday.

Ozzie

When it comes to minuscule leaks, I have found myself in prayer to mine, but others have told me not to make it into a god.

MDchanic

Curse you, fingers!

- Eric

My2nd 69 442

Junkman
When you pressure check the system with Nitrogen, what pressure and where do you pressurize the system. I have a nitrogen bottle and can pressurize the system for several days at home, then have the system vacuumed and serviced.
Thanks for your tips

budg

There is no reason you shouldn't go to 100 lbs of pressure. The high side will likely see that type of pressure when it's running. Like someone previously said , make sure the refrigerant is completely out of the system or your pressures will fluctuate with temperature. You can use soap bubbles to check for leaks at the joints . If you do have a leak it's important to know where it is.

MDchanic

The high side can see 300-350psi.

- Erc

Junkman

There is no question that every one of my systems are clear of any refrigerant, since I almost always change the O rings and the receiver drier, if I have to do any major service of the system. I have a bottle of Nitrogen, and I just put in about enough to get it to 100 PSI, give it a few minutes to normalize, and then take my readings and let it sit. Then slowly bleed it off, and then pull my vacuum again.
I am always paranoid about loosing oil, or when putting oil into the compressor having the compressor bind up. For this reason, I always put power to the compressor clutch, and turn it by hand a bunch of revolutions. I learned A/C work over 50 years ago by trial and error method. Experience is a great teacher, even when you do it wrong. You hope to never make the same mistake twice. Just remember, that cleanliness is the most important thing to remember when doing any A/C work. In the old days, I was quite careless about this, and I always got away with it, but today, I know better.


If you are in need of Viton O rings, search eBay for "270pcs 18 Sizes Car Vehicle A/C Air Conditioning HNBR O Rings", and if you want to make an offer, offer $8.00. That is what I did, and he accepted my offer. I doubt that you will find them less expensive anywhere else...

Fun71

I thought I would mention this so no one has the same issue I experienced.

Years ago I pulled a vacuum on the system and let it sit for over 24 hours to ensure no leaks. All seemed good so I charged the system and ran it for several years. Eventually it ran low on refrigerant and I discovered there was a slight leak at the low pressure Schraeder valve. I didn't notice the leak when I pulled the vacuum because I left the gauges connected to both the high and low ports for that 24 hour period so I could monitor the pressure. Doh! So the lesson is disconnect the gauges, either both or one at a time to check the valves for leakage as well as all the other connections in the system.

budg

Without a doubt, especially in the SW where temps get in the 100s. Car systems are unique in that they are designed to take a space that could be 160+ degrees and bring it down to 70 in a matter of minutes.

CRUZN 66

IMO R12 is the way to go if you truly want originality... As judging goes, if you are entered into an "Original Class", and the Freon fill valves are not correct, points can possibly be deducted... Depends what judges may or may not want to overlook... Could come down to a matter of tie breaker points for best of class in OCA National Judging rules...

Rocketguy

Anyone could easily remove the adapters for a show and then reinstall them. It would not drain the charge.

MDchanic

I think they're required by law to have some kind of barbs on the threads so you can't unscrew them.

I could be mistaken...

- Eric

Funkwagon455

I had thought that there was some type of thread locking medium in the adapters for R134 as well, but not certain. I think that the adapters are beside the issue and it really comes down to owner/operator's choice. I won't argue the cost of R134, it is much cheaper and much easier to acquire. For me, there are more reasons to continue to use R12 as stated in my first post on the subject. Thank goodness I had the foresight to purchase 45 pounds of R12 when I was working in Bolivia!!!

Junkman

R134 fittings are barbed, and they will destroy the original fitting if you try to remove them. At best, you might be able to cut them off using a Dremmel tool, but be prepared to spend a lot of time doing it, and you always run the risk of ruining the original fitting. When you consider the cost of changing the compressor oil, and flushing the components to add the R134, it isn't as inexpensive as you might think. There are some shops that don't care about doing it the correct way, and those are the places that will just pump R134 into your system, not being concerned about how well or how long it will work. If you loose your original R12 charge, then the prudent thing to do would be to find out why you lost it. The other thing about R134, is that the molecules are very small as compared to the R12 molecules, and they will migrate through the lining of the old hoses. That is why all the new cars are using a barrier hose. I doubt that you could even find the old rubber hose that was used for R12.

Fun71

I found this on an AC web site where someone had said a similar thing about molecule sizes:


http://www.acsource.net/acforum/view...php?f=1&t=8578

Junkman

As if we didn't have enough to worry about, while researching the molecule size, I came across this... http://www.autoacforum.com/messagevi...&threadid=8761 ... now we have to worry about water getting into our A/C systems. Then I found an article from 2003, saying that Viton O rings shouldn't be used with R12. Further research came up with this "Technical Paper" that said that HNBR was a "good" O ring for R12 & R134A.




Now, I am feeling pretty good about using what I think are Viton O rings in my R12 system, so I decide to do more reading. Further down the page, I see the chart suggests HNBR as "good" and "Super Neoprene" as "excellent" for R12. Another half hour of reading, and I finally find out what Super Neoprene is...
Then I find this PDF (HNBR70 Durometer, Green color) and I start thinking that HNBR is Viton... a little more reading, and I learn that Viton is a trademarked name of DuPont. OK, they are both the same thing, only using different terms.


Now, by this time, you are probably asking yourself, where is all this going. Honestly, I myself, don't know. The more that I read, the more confusing all this gets. OK... I know that some or all of this must be true, because I read it on the Internet, and everyone knows that if it is on the internet, it has to be true. Even the mobile air conditioning websites can't seem to agree, what is best, what is right, what is wrong, what is ... etc..

In conclusion, I really don't give a dam about R12, or R134A, rubber hoses, barrier hoses, small vs. large molecules, PAG, or Mineral Oil, or anything else. I am just going to put some Freon into the system, and if it all leaks out next year, I will let the next owner worry about it. I know that all the experts, including the keyboard warrior experts don't agree, and all this reading this evening is making my eyes tired, and my mind confused. Let us all agree to disagree, roll down the windows, and enjoy the hot humid air without conditioning.


PS... Ever wonder who owns the word "Freon"?


https://en.wikipedia.org/wiki/Freon

Rocketguy

Great info junkman, thanks for posting.


I just removed one to replace the schrader valve and it was not barbed. Maybe it was a cheap one and I got lucky?

cjsdad

Something that hasn't been mentioned yet is the difference in condensers between R-12 and R-134 systems. I was working in an A/C shop in Phoenix as an installer when the Big 3 were transitioning their A/C systems over to the R-134 refrigerant and there was a change in the condensers during that time. The older ones used a continuous (serpentine) flow and the newer condensers use a parallel flow design in order to maximize the cooling down of the gas. I don't know if the design was used before or not, but we had a devil of a time getting the R-134 conversion systems to cool properly if an older condenser was used. There were other issues as well, but that was the biggest. Because of the severe temps in Phoenix we had to get creative with the way we sealed the air flow through the condenser and radiator to maximize cooling. We also gave up on the barrier/no barrier hose issue and just used the new barrier hose on everything.

1969w3155

My buddy converted to R134a on his'68 442 a couple of years ago at the insistence of the a/c shop, I'm not that impressed with it, I mean it's better than no a/c in mid summer, but it takes a long time to cool the interior down and doesn't get really cold.

cjsdad

Just like your home A/C system, you can modify your old system to perform better, but it will not work as well as a fully re-designed modern system. The old R-12 systems worked great but were not all that efficient. Have your buddy fill all of the gaps around his condenser with insulating foam rubber weather stripping (not expanding foam from a can!) so that all of the air is forced through the condenser on its way through the radiator and it will help. A good fan shroud and fan clutch will make sure you get the most air through the condenser and radiator at low speeds and sitting in traffic. With a retrofit system, it's the little things that can make the biggest difference.