I have two vehicles that both use R12 and I am going to have to get at least one of them charged. However, I am not willing to pay a mechanic some $150 dollars to do something I should be able to do myself.
From what I can gather, R134a is not an optimum choice for replacement. It does not cool nearly as efficiently in the R12 system (major consideration in a Texas summer), requires the compressor to operate at pressures it wasn’t designed for, and will leak out fairly quickly no matter how tight the system is.
A quick search on the web brings up a large number of self-touted direct substitutes for the R12 that the makers say will cool better or are more eco-friendly than either R12 or R134a. Apparently some of these products are regulated as the distributors offer certification “classes” you have to take to keep our friends at the EPA happy.
However, I am loathe to trust a company’s own testimonials about their snake-oil.
So, does anyone have any experience with the HFC based replacements (Brand names such as Freeze-12, McChillit) or with the HC based ones (Envirosafe, Duracool)? Any suggestions on which ones seem to work best, problems noticed afterward, how well they held up?
Boxcar, I’m not an AC expert, but here’s my 2 cents (and a bump to the top for this thread):
The seals are already somewhat worn in you compressor. I would guess that evacuating for any coolant change might damage them further.
The aftermarket and AC shops have had a decade to get used to 134a. Even if they work, knowledge about those R-12 replacements will be hard to come by. If nothing else (and if you can’t find/afford R-12), you might replace your compressor and just make sure that the replacement is ok for 134a.
If no one else here can offer better advice, you may want to try an air conditioning message board (they exist, but I don’t have a URL.)
Sorry for making this so abrupt, but I just posted a reply here, and I have no idea where it went.
The compressor and the system has tested out okay within the past month but would need some repairs before it could take R-12. I’ve got some bad O-rings and other seals that leak just enough to disqualify it. Since I plan to get rid of the car by the end of the year and I didn’t want to go spend a lot of money on repairing the system, I figured on charging it with the enviromentally friendly stuff and letting it leak. If it lasts three or four months that would get me through the worst of the summer.
I will probably just be a guinea pig myself. Or, heck, it’s only another 45 days or so before the temps start dropping below 100 again…
Some of the alternitives are propane-R134a mixes and does cool better then straight 134a - but in old systems the propane will leak out fast (smaller molecule) leaving you with a lesser quantity of 134a.
If you can’t afford/obtain the good stuff then I would go and buy a 134a conversion kit for about $20-$30 which is just valve adapters and 134a oil and a few cans of 134a. You just add it to your existing system. I might be even tepmted to leave any 12 in there and just mix the 2. This will most likely be the cheepest way to go.
As for if it is cold enough - I don’t know how your F12 system is - I had a car that would form frost on the windows (and cut m/g in halve) I have no doubt that 134a conversion would be fine. Then I had one that was very poor and would never consider converting unless that’s all I could get.
Also if you do convert backflush your condenser (with a hose) - keeping the condenser clean will help all a/c’s but esp. a convert.
BTW F12 is a very small molecule (IIRC F 2 Cl 2 C {spaces added}) Is 134a smaller?