Here's some controversy - propane instead of R12

[John Hubertz]

Regarding R12, one good "cheat" is to use propane....but you need to be sure you've got a pretty tight system.  One nice thing is that if you do have a leak, it will stink.  Gotta be careful though...since it is flammable.  No more flammable then gas of course.... and due to the system being pressurized even a "flaming" leak will likely self-contain.  Don't believe the movies with their big explosions.  Our local '60s hot rod community has been running propane for years with no fires.

The big issue with R12 is that the molecules are twice as large as the non-CFC refrigerants (but slightly smaller then propane) and of course the cooling capability.  An old system will almost certainly be porous to R134a because compressor tolerances were huge compared to modern compressors.

Two things - be darn sure you've got a tight system if you top with propane (don't use it on a car that is totally "flat", which means you have a leak), and also tell any future owner or mechanic, since older freon "sniffers" use a flame or hot wire to check for leaks.

Also, use one can of the commercial 134a FIRST....  get the kind with the leak stop additive at your local wal-mart.  This will serve to charge the system with a good dose of new oil as well as a seal lubricant.

(laughs)  Let the angry comments.....BEGIN

John Hubertz

[oscar]

Hi John,

Firstly, sorry for ambushing your last thread with the great a/c debate.

Secondly, glad to see you wanna keep going.

I think the probability of me obtaining one of these US DIY conversion kits in Oz is diminishing.  I haven't thrown in the towel yet, but funny you mentioned propane. 

I found an Aussie site http://www.hychill.com.au that make an R12 replacement which is called HR12.  Looking up the MSDS or tech sheet, it's a 50:50 mix of propane and isobutane.   Sorry, but sounds like I'd lose more than my eyebrows.  But as you say you need a tight system.  Mine is flat.

[oscar]

Here's an interesting post re: HR12 quoted from the MB club of nsw forum that has HR12 in his system.

"....but I can advise that the use of HR12 is the best thing I have done for our cars.

The "cool" air conditioner is now ICY COLD.

HR12 is a flammable gas, so many people shy away from it on safety grounds, but remember that if you are driving a petrol car, you have a significant amount of liquid which can provide vapours as explosive as propane. In my 300D, there are 320 g of refrigerant. This is around the same as 400 mL of petrol, in explosive power.

How much petrol is in your engine bay? "

I may be off the freeze 12 bandwagon and onto the HR12 train.  Now where do I buy seals?

[alabbasi]

I bought R406a to use in my R12 cars. It's propane based and is designed to mix with the R12 oil.

[boneheaddoctor]

but will propane circulate the lubricant....I seem to remember thats the main issue besides the flamibility?

[boneheaddoctor]

If I had not already gotten some R-12 I would try that....I do want to suck out the R-134 that a sticker say s is in it and replace it with R-12 because I am real unhappy about the performance of that (was in the car when I bought it).   I do have to repair and recharge my W123 in the next couple months....boy I hate to sweat in traffic.

You may want to think twice before you use a leak sealer....if you ever have to open the system that stuff cures in the presence of air and will render your system scrap.