Conversion to Freeze-12

[FastWoman]

Steve, I mean the mineral oil. As I understand (note: I'm no A/C expert. I've just done some reading...) the ester oil is considered compatible with residual mineral oil when doing a 134a conversion, and it's of course very easy to find. However, that doesn't mean that the ester oil gets along optimally with the R12. I've been told technicians do add ester oil to R12 systems, but I simply erred on the side of caution and used the original variety of mineral oil. It was probably unnecessary to do so, but I always prefer using the original stuff, rather than something that's compatible with the original stuff.

[Wade Nelson]

Yes, you can get a system that's low on Freon working again, somewhat, by adding Freon. Fixing the places its leaking, is of course, vital.

But what's gone missing from this discussion is the importance of evacuating the system, and replacing the receiver/dryer. That is, using a vacuum pump to suck every last bit of air out of it. And boil any water out of it. (Water boils at room temperature in a vacuum)

In the olden days you used to pull a vacuum and let the AC system sit overnight. These days the pumps are better.

Simply putting an empty R12 can in an ice bath ain't gonna do much to the remaining air/water vapor in the system, even if it does condense out a few droplets of R12.

As far as being "ecologically correct" virtually every car made from 1964 to 1993 eventually lost its freon into the atmosphere, that's tens of millions, one more pound of R12 isn't likely to destroy the ozone layer. The only "real" reason to recycle it is to avoid buying more, but since yours is 99% likely to be contaminated.....

The EFFICIENCY of your air conditioner, whether it's R12 or R134 based, is determined SOLELY by the amount of water (vapor) and air CONTAMINATING the system when you are all done. Even a tiny amount can reduce your efficiency by 50% or more. You put it on HI and only get cooled air instead of 34 degrees freezing you out.

This was the "big truth" I learned after years of replacing parts, sealing leaks, adding more refrigerant, etc. It's not how MUCH R12 you've got in there but how pure it is.

The receiver/dryer is chock full of the same stuff in those little silica bags that come with new products. Its job is to absorb any water vapor that gets into the system -- by way of humid air that sneaks in.

After 20 years, your receiver/dryer is most likely saturated. It can no longer do the job it's designed to do. Replace it, especially if you're springing for a new compressor. (Front seals on compressors --- #1 leak spot for refrigerant)

Once you've FOUND all the leaks in your system, and sealed them --- new hoses, new o-rings, leaking schraeder valves (Nissan replaced a lot of these when I worked there...) and front seals on AC compressors, and condensors with pinholes in them from rocks hitting 'em.

Again, once you've FOUND all these leaks and sealed them, THEN it's time, along with a new receiver, to pull a mighty vacuum on the system, to suck 99.9999% of the air out. This will ALSO "boil" any remaining water / water vapor in the system allowing your new receiver to do it's job effectively.

So often it's a two step process, you shoot in a SMALL amount of $$$ refrigerant and dye, identify and seal the leaks, THEN replace the dryer and pull the big vacuum, and go for the final charge.

The equipment is called a "micron" gauge, and a "micron" pump, which pulls your system down to, say, only a million molecules of air and water. They're not cheap, which is why only AC professionals own them. I happened to get lucky and find one in a pawn shop. Along with the halogen detector you need to "sniff" really small leaks, like out the schraeder valves. We're talking a few thousand molecules a minute.

And the other thing is, if you add Freeze-12 or R134 with "stop leak" in it, no AC professional will ever work on your system for you. That stuff will RUIN their expensive gauge and pump. so they test your system for it before they hook up to yours.

Now really, with 150 psi, do you really think adding some "goo" is gonna stop your refrigerant leak? Sure, maybe 1 out of 10 leaks will be healed by it. 90% wont. How often does "slime" actually work to fix a flat tire on a bike?

I was wrong in an earlier post, R12 on Ebay seems to have declined in price, considerably. So a R134 conversion is no longer economically mandatory. But remember, you'll probably waste ONE can of R12 just FINDING your leaks.

I'm not telling you you can't, or won't have some success working on your own AC system, as Fastwoman proves right here. But finding and working with a true AC professional, and doing it right, doing it once, which will NOT be cheap, can in the long run be cheaper (and far less frustrating) than doing it piecemeal, and only getting mediocre results.

The best AC man in the USA is a guy by name of Glenn Farrell down in Louisiana. He's the one who "educated" me.

Good luck!

[ZCurves]

Yeah, I could have used one of those! Harbor Freight? (I didn't look there.)

The Colonial Parkway is great, but so are parts of Texas. Brenham in the springtime is one of my favorite drives. One particular drive through the Brenham area was the closest thing I've ever had to a religious experience.

True... MMM...Blue Bonnets, Blue Bell Ice Cream....and Sausage, but not Sausage Ice Cream.. But wait..... Nah too salty. :classic:

[FastWoman]

Ahhhhh, yes... Blue Bell ice cream.... You're making me homesick, Andrew!

Wade, to be clear, I did use a vacuum pump (bonafide A/C service variety) to evacuate the system. I didn't replace the receiver/dryer, though, as I didn't have an open system. Total freon leakage has been about 2 lb since I've owned the car, so it's not like anything has been hissing. I also didn't add any goo products -- don't believe in them. FAIW, my A/C blows very cold now.

Edited May 23, 2012 by FastWoman

[Wade Nelson]

Here's another refrigeration tidbit I just learned:

>Any excess liquid becomes stored inside the condenser – and any excess liquid decreases system refrigerating capacity. Generally speaking, a critically-charged unit should be charged within ±1-2% of the listed charge.

All halocarbon-based (R12, R134, ...) automotive refrigeration (AC) systems are "critically charged." They can't just store excess liquid Freon somewhere. like ammonia-based commercial systems do. Every ounce of EXCESS freon liquid displaces vapor in the condensor that would OTHERWISE be helping cool your car.

So in other words, don't OVERCHARGE your system, thinking it will blow colder. It will actually DECREASE how well the system operates.

It would be great IF automotive AC systems COULD store a Dewar flask of liquid something so you could have INSTANT cold air the moment you flipped the switch, like how the Prius stores hot engine coolant for faster warmup, heat, defrost, and decreased emissions.

Someday.