And it's tough to patent ammonia, propane and isobutane so they will never be approved for use in auto refrigeration. Using anhydrous ammonia as a refrigerant in an absorbtion loop would let catalyst heat (or battery/electric motor heat) do most of the work with no compressor needed. Except for the annoying problem of carrying a system with a few ounces of deadly poisonous gas inside, a no-moving-parts AC system would be pretty cool.

 

We are one of the only shops in Utah still working on R-12 systems and have lots of business including Porsche dealer hand-offs. R-12 is not as easily available as it used to be but it is still out there. I personally have converted a few cars to R134 and will never do it again. Pressures are higher and the systems are not getting any younger. My experience with every conversion is that at highway speeds R134 cools just fine but when you need it the most, stopped in traffic or in town it is marginable at best. That has been with optimized, fully rebuilt systems so no excuses there. Every single conversion had the same results. I will still do conversions if the customer insists but they will sign a disclaimer that it is what it is, no complaints.

 

I wouldn't really say NH3 is that deadly. I've gotten a face full a couple times working on diffusion equipment. Sure, it's unpleasant, and will make your eyes water and you will cough like there's no tomorrow, but in the amounts needed in a car cooling system if designed properly would be no more dangerous than all the other stuff we put in AC systems.

It readily dissipates in the atmospheric conditions where cars are used and stored, and the noxious effects cause people to rapidly get away from it(as I well know). I wouldn't hesitate to use it in a well designed car AC system, but then again, I don't have a mangina to worry about.

Now, if you want to talk about your nasty stuff, I can tell you the story about the time the over-pressure valve let loose on the gas tray and spewed POCl3 out there. Boy! that was a hoot and a half. We had a 3 foot flame of acrid green/yellow crap screaming across the clean room. What a day...

Then there was the time I was working at the Ft Saint Vrain slurry reactor running the U(235)F6 (Uranium hexafloride, for giggles). Lets see if I recall; spontaneously fissile in air, spontaneously combustible in air, spontaneously etchant in air, highly toxic, will melt(chemically, nuclear) tissue on contact, etc. That stuff was kinda serious.

 

Has anyone met Doc in person? Does he have three arms and an extra ear or two?

 

My kids are smarter than you, must have been worth the exposure.



<edit: Did you get to KOSH airventure this year?>

 

Let's be clear - it leaked out and wet air likely leaked in too.

So - what Dr Bob said - at this point either way you go it makes sense to clean it out, replace all the o-rings, dryer etc & pressure test... so that makes an R134a conversion a much easier choice. If done right it should be fine.

Alan

 

No........

We were traveling so much this July we just didn't have time to swing down there.

 

Being in the biz....I subscribe to the "for profit" conspiracies.

As for R 12, I think it is much more effective than 134a. I have 30# in personal stock! that will juice my 928 quite nicely, when the time comes.

 

Roger

What is your price on r12?

Thx

 

$35 a can

 

Thanks for the steps to get the system working and the advice regarding 12 vs 134.

There is a shop in town ( EuroSport Naples Fl ) and the owner said he has owner four 928s over the years liked r12, but could not get r12 and suggested converting to 134 or even trying freeze12 (nah, I'm thinking no freeze12). Overall he seemed to know his stuff and had a Boxster, 968, old XKE and 308GT in his shop ... so it seems that other customers have some faith in his work.

First I would like to get some r12 from Roger to see if the shop can get it working & how it works since it was o e in 87. Then I try to keep tweaking the system on my own.

 

my system is still r-12, it does have a slow leak, traced to the compressor, last charge was two years ago, but needs a refresh. Luckly I have a local shop with a r-12 supply. But he charges $45 a can roger.