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-   -   R12 or R134? (https://www.airforums.com/forums/f311/r12-or-r134-99110.html)

Astrodokk 12-01-2012 09:48 PM

R12 or R134?
 
When I bought my moho back in 2002, it had been converted to R134 using the old R12 hardware. It worked ok but just didn't cool very well when really needed.
Today I took the old gal to an AC repair shop and the owner said I could repair it or go back to R12, which will work better in the system that is still installed.
I know that R12 is a lot colder and that R134 wasn't working very well before, so I'm pondering going with R12. I have until Monday to advise him of my decision. What is the consensus on this? I asked about Sanden R134 and he said that Sanden compressors aren't as good as the original that I have still in there. He said if it was his rig, he would stay R12. He will charge me $80.00 a pound for it. I know R134 is $30.00 per pound. I'm in a dilemma. What should I consider?

ROBERTSUNRUS 12-01-2012 10:51 PM

:) Hi, first I would take it to an automotive A/C repair place, not a general mechanic. [if you haven't already] Then I would have them check the system for leaks and for a proper charge. Might be a lot cheaper to replace a compressor seal and recharge to the proper amount of refrigerant, if that's the case. R 134a should cool just fine.

idroba 12-01-2012 10:59 PM

Too bad you can't do the work yourself as my first recommendation would be to go the R12A which is a propane based refrigerant. It is legal for you to put it in, but not the shops. That is a very long story which is hard to get into. The GMC motorhome community has been using it extensively with excellent results. It is about $6 a can and you need about 2 to 3 cans max.

But if you can't do the work yourself, it is hard to recommend what is best to do. R12 is about 15 to 20% better than R134a from the cooling standpoint, when used as a replacement refrigerant. The early AS motorhomes such as you have had a somewhat marginal Air Conditioning system to begin with. By 1983 they were better.

You are probably going to be charged for 3 to 4 pounds of refrigerant. At $80 a pound for R12 that is a lot of money and unless you have a very very tight system, in a year or two you will need to do it all over again. I guess a shop will charge $30 a pound for R134a, but it is available for your own use at 1/3 to 1/2 that price.

Keeping an old Motorhome AC system going is a constant battle, and again the one you have was marginal to begin with. If it were mine, and I could not do the work myself, I would stick with R134a, simply because of the cost of R12 and the availability. Or, run your generator on the road, and use your roof air. At those refrigerant prices and the labor to put them in, the gas for the generator seems like a bargain to me.

That is my opinion anyway...

TBSarfari28 12-01-2012 11:50 PM

I agree with Bob, take it to a auto A/C shop that has EPA section 609 certified technicians. There are EPA approved replacement refrigerants for R-12 that will cool as good as R-12. R-134a in your system will not cool as well. Changing your compressor will not help the cooling using R-134a, unless you increase the size of your condenser, which you may not have room for. Check out the list of approved replacement refrigerants for R-12 (Substitutes in Motor Vehicle Air Conditioners | Alternatives / SNAP | US EPA) for use in motor vehicle air conditioners. Most require 90% to 80% of the orignal R-12 charge, and cool as well or a little better than R-12. I have used Autofrost and it works very well. Any replacement refrigerant that is flammable should not be used in a motor vehicle A/C system as per the EPA Snap program. I have seen vehicles catch fire when there was a refrigerant leak in the engine compartment. Not Good for your motorhome.
Good luck

Bob4x4 12-02-2012 09:36 AM

R12 does cool better but one day soon it will not exist,right now there is a problem with counterfit refridgerants coming in from off shore sources.with that comes the risk of flamable hazards. One of the posters above stated you can buy and install r-12-not so unless you are licensed.The installer who recommended going back to r12 may have been trying to unload his obsolete r-12.Good luck with your decision

perryg114 12-02-2012 10:31 AM

Don't tell anyone but you can get R-12 cans on Ebay. Give then to your AC buddy and just say you found them in an old cabinet.

R-12 in eBay Motors | eBay

Astrodokk 12-02-2012 12:25 PM

Wow, so much to think about. Ignorance is bliss as they say!
The only difference in this project is the refrigerant. This guy is a licensed automotive AC technician and does all vehicles including motorhomes. He has one too. He's going to pretty much replace the compressor, accumulator-drier, rebuild the hoses, chemical flush, AC oil, then add the refrigerant. Notwithstanding the parts prices, his labor will be $250.00. So with all that being the same except for the respective nozzles, I need to decide.
Thanks for the ideas.

Keyair 12-02-2012 12:47 PM

$80/ Lb for R12....
Oh my...

Shame you dont live closer to me....
Look what I have in my Garage...

https://www.airforums.com/attachments...b5c3c9ce5f.jpg
https://www.airforums.com/attachments...78abc9930b.jpg
https://www.airforums.com/attachments...1692be8e89.jpg
I bought a virgin 30lb can of it for $200 about a year ago locally...
You can do your EPA 609 licence online for $20 and its an open book test...
EPA 609 Certification

I have used ES12a too....
But last time I mentioned it here, I got into trouble for saying it..
It works great, but if you are worried about having the fire risk of propane based refridgerant onboard, I would not suggest you use it...
Refrigerant - Enviro-Safe Products

I replaced every O ring in my 1990 Mercedes 190E, with HNBR O rings, and recharged it with R12...
85degF in my garage, and I was getting 35F out of the vents at 2000rpm in my garage with just the fans running.
https://www.airforums.com/attachments...4f7832ba75.jpg
https://www.airforums.com/attachments...092606be84.jpg

robert claus 12-02-2012 01:30 PM

Putting 134a into a system built for R-12 will provide cooling, but probably not for very long. The 134a will escape through any rubber hoses, as the molecules are smaller. You'll need to change any hoses to a barrier type, which is kind of like a hose with an internal lining. Also, you have to change the compressor oil to once compatible with the 134a.

Keyair 12-02-2012 01:32 PM

Agreed too Robert.
Change all O rings as a matter of course, as the originals are not only incompatable but go hard and brittle.

AtomicNo13 12-02-2012 01:41 PM

in 1994, I retrofitted the Schrader valves of one of my old European cars originally designed for R-12. It lost all the R-12 due to a failed compressor. I then added R-134 and it cooled great..... and has ever since. I have never topped it off, nor have I experienced any leaks!

Long story short... it is worth a few bucks.

You'll have to evacuate all the old oil from the system, and replace with new.

Remember I said 1994... it is now 20 almost 13!

Smartstream 12-02-2012 01:43 PM

Save your money and run the 134a. No matter how much money you spend your dash air will never cool your coach.... period, end of story and anything you want to say... an auto/SUV sized unit will not cool a 28' coach. Add the shiny aluminum and the huge glass area up front it just will not get cool. At best you can take the edge off a bit. You can argue whether R 12 is 10% more efficient than 134a but when you are going down the highway and it's 100 degrees outside you are going to be hot inside your coach unless you drive with a bucket of ice in your lap or use something else in addition to your dash air.

Good luck, Dan

Astrodokk 12-02-2012 02:31 PM

Quote:

Originally Posted by Smartstream (Post 1233535)
...period, end of story and anything you want to say...
Good luck, Dan

Gulp.:sad: LOL

Actually, I don't mind that it doesn't cool the whole interior. I've read that you can drive with the generator on for the roof AC. I'm merely interested in having cold air blasting in my face while driving. That R134 just didn't cut it when I first bought the moho, as the PO had just done the conversion. You all are right, though, the stuff went out the hoses eventually. Man, I know I'm gonna get flamed, but I think that I will have it go back to R12 and let an eventual new owner decide to go R134 if wanted to later. I know that others prefer R12 as I've received some PM's that want to remain anonymous due to avoiding conflicts here (don't know why, I think I've seen many different opinions dealt with very courteously in this forum), and I understand and appreciate those. Key, you're the only one who's admitted publically so far, of getting reprimanded for your controversial alternate method. But then again, you have all those rivets!
As much as I am a cheapo when it comes to spending money on stuff that I can do myself, I've also been advised to let a professional deal with this type of system, at least in it's upgrading. He guarantees it for one year. He said if I use R12, if it performs well for the first year, it will go for a lot longer.
Thanks for all the rappor!

perryg114 12-02-2012 02:33 PM

I sort of agree with Smartstream. If it is still cooling leave it be. Have you measured any temperatures to see how well it is cooling? If you have something close to 20 degrees below the ambient temperature you are doing well. A curtain can reduce the volume you are cooling.

Perry

Astrodokk 12-02-2012 03:19 PM

Sorry, I guess I didn't mention the reason I'm doing this! The compressor is fried! It doesn't work at all. I had to disconnect the wiring so that the clutch doesn't try to engage and make a racket. It still makes a terrible noise since the belt is still attached. The system lost all the R134...completely empty. So, it doesn't cool at all. Can't leave it be, because I'm going to LA in June (Keyair, are you close to Glendora?), and I'm not going without AC.
I'm going through all the systems again so that I can use them in a pinch, and I don't want to have to if I break down.
I'll recap in a different thread about what all I've done to this baby since I bought her ten years ago. I like the idea of sort of a blog as you go thread like some of you have. I wish I did that from the beginning.

perryg114 12-02-2012 03:30 PM

There are things that can be done to make a 134A system work better. Things like replacing the expansion valve with the correct size. I think they also make condensers that are designed for 134A. It is hard to keep any old system leak free so 134A would be cheaper. I have never noticed a difference in cooling in R12 versus 134A systems. Retrofitting an old system may make it a little less efficient. To do this right you need all the soft components replaced anyway so you might as well get 134A compatible hoses and seals. What you don't want is a leaking old system with R12 in it because of the cost and limited availability not to mention the enviromental concerns.

Perry

Smartstream 12-02-2012 03:39 PM

I had a belt drive problem and thought it was the compressor clutch going bad so I picked up a rebuilt unit from O Reilly's to continue the trip. The first compressor was a new old stock. About 12,000 miles later the OReilly compressor failed so I reinstalled the NOS compressor. I made the swap at an RV Park in Bronson, MO. I drive with a pocket thermometer in the vent so I can keep an eye on the A/C. The NOS compressor ran 8 to 10 degrees cooler at the vent with no other changes in the system.

The condition and quality of all the components in the system make a difference.

Cheers, Dan

Keyair 12-02-2012 04:06 PM

All great points!
I love your idea to run with a pocket thermometer in the vent Dan!
I posted a link to a great R134 retrofit PDF... but cant find the link now..

When I get to the time to fix our engine AC, which has retrofit R134 fitting on it, but is empty AND has the clutch energizer wire cut off... I will have to make some choices too. One thing I will look at is adding a 2nd evaporator somewhere in the cabin!

ROBERTSUNRUS 12-02-2012 05:15 PM

Quote:

Originally Posted by Keyair (Post 1233519)
$80/ Lb for R12....
Oh my...

Shame you dont live closer to me....
Look what I have in my Garage...

https://www.airforums.com/attachments...b5c3c9ce5f.jpg
https://www.airforums.com/attachments...78abc9930b.jpg
https://www.airforums.com/attachments...1692be8e89.jpg
I bought a virgin 30lb can of it for $200 about a year ago locally...
You can do your EPA 609 licence online for $20 and its an open book test...
EPA 609 Certification

I have used ES12a too....
But last time I mentioned it here, I got into trouble for saying it..
It works great, but if you are worried about having the fire risk of propane based refridgerant onboard, I would not suggest you use it...
Refrigerant - Enviro-Safe Products

I replaced every O ring in my 1990 Mercedes 190E, with HNBR O rings, and recharged it with R12...
85degF in my garage, and I was getting 35F out of the vents at 2000rpm in my garage with just the fans running.
https://www.airforums.com/attachments...4f7832ba75.jpg
https://www.airforums.com/attachments...092606be84.jpg

:) Hi, and I think I have a few loose cans of R 12 in my garage. I also have a 30 lb can of R 12 that has been sitting in my garage for about twenty years.

Keyair 12-02-2012 05:17 PM

Quote:

Originally Posted by ROBERTSUNRUS (Post 1233597)
:) Hi, and I think I have a few loose cans of R 12 in my garage. I also have a 30 lb can of R 12 that has been sitting in my garage for about twenty years.

First Dibs!


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