CoolingDiscuss all of the aspects of cooling that you can think of! Radiators, transmissions, electric fans, etc.
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I finished the conversion of my system to R-406a or autofrost. All the stories Reid and the others have been telling is true. It's unbelievable. My A/C was never this cold before and definitely wasn't this cold when I converted it to R-134a initially. So, for anyone wanting to make the conversion, don't waste your time with the R-134a: get some autofrost and do it right the first time.
I took an infrared thermometer and shot it at the vent, where it said the temp was 17.2 °F. I don't believe that for a second, but it is definitely cold, probably around freezing temp; I'll try and get a picture of a regular thermometer after I scrounge one up.
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I finished the conversion of my system to R-406a or autofrost. All the stories Reid and the others have been telling is true. It's unbelievable. My A/C was never this cold before and definitely wasn't this cold when I converted it to R-134a initially. So, for anyone wanting to make the conversion, don't waste your time with the R-134a: get some autofrost and do it right the first time.
I took an infrared thermometer and shot it at the vent, where it said the temp was 17.2 °F. I don't believe that for a second, but it is definitely cold, probably around freezing temp; I'll try and get a picture of a regular thermometer after I scrounge one up.
That's awesome! Where did you pick up the R406a?
I have found the R134a conversion to work pretty good, but colder is always better!
Does that thing shoot out ice cubes? if the temps that cold you can bring along syrups and sell slushes at the car show!
The laser temperature guns for some reason don't give accurate numbers. Digital thermometers do though.
Last month, I had been throwing around the idea of putting in a parallel flow condenser with Autofrost to see what kind of "maximum cooling" situation I could get. They're advertised as being 30% more efficient than our tube and fin style condensers. But before doing that, I wanted to try out how well the stuff worked with just the stock condenser, stock fans etc.
I adjusted the low pressure cycle switch down to the 6 o'clock position on my car (aprox 18 psi which would give a min temp of 20°F before cycling off)
With 83°/53% outdoor conditions, I went for a drive. Ohhhh brother. It went down to the 27°F zone and hung around there for awhile. Turning the fan speed down, it went down to 24.7°F.......At that point, I pulled over and popped the hood. Who wants a slushy?
There are a few things wrong with running the A/C this cold:
The hood insulation will stick to the iced up accumulator. Not a lot. Just a little black fluff that will wipe off with your finger.
Turning around and driving home with it blowing 25° air on me, I started to shake from the cold.
It will fog up the outside of your windshield, requiring you to either turn up the temperature or turn on the windshield wipers. This is due to the interior of the window being colder than the outdoor dew point. (this only happens in hot-humid climates)
Bright white glowing layer of snow on the suction line running from the accumulator to the compressor.
Why waste fuel running the compressor when it's unneeded?
I'm sure it probably could run even colder if I really wanted it to. But at 24°, I was shivering. It was rare for the outside air to get that cold during the wintertime when I lived in Canada never mind having a "windchill" blowing on me in the car in Texas in September.
I now understand why the creator of R-406a used to get kidded for creating pneumonia in Florida during the summertime back when he had the stronger version of Autofrost. That stuff would blow 25° at the stock low pressure cycle point.
Driving on the highway at 60 mph, my car would sit at 29-30° duct temps. Below 40 mph (when the radiator fans turn back on), it would go down to the obscenely low temperatures mentioned above. So it appears that the stock condenser is maxed out on it's own around 30° or so. I do have a fairly large 11" x 12" transmission cooler in front of the condenser (not touching it). Without that, it may run cooler. Who knows.....
I decided against going for the parallel flow condenser. Quite honestly, I just don't need it. I can live with 30° on the highway and as cold as I want around town. Putting the parallel condenser in would just result in faster cooling and more cycling.
I turned the low pressure cycle switch up to around 24 psi so that it would shut off the compressor around 27°F. But after a few days of that, I decided to just put it back to where I had it before. (stock 26 psi giving a low temp compressor off point of 30-31°) With the stock pressure/temperature point, the car will drip mammoth amounts of water. When I was running at 24°, not much would drip until you went to VENT or shut the car off. At that point it would literally spray water onto the ground.
One of the most common questions people ask me is doesn't the system turn into a giant ball of ice? No. Ironically the duct temperatures will drop faster from 30 to 25° than they will from 35 to 30°. Once you get it down to super cold levels, the low side pressure drops like a stone. It would sit blowing 26-27° air on me at stop lights with traffic in front of me. Yet if it was at 33° at that same stop light, it would tend to rise up to maybe 35-37°......Now that fast drop in temperature (and low side pressure) is what causes the compressor to cycle off and melt any ice. Of course if you've got it intentionally set so that it won't cycle off, well yeah the system will ice up.
I can see why it's recommended that you have antifreeze in your coolant system. The heater core would freeze. When I was running at 24°, my dashboard on the passenger side was very cold to the touch. Oh yeah, one more thing. With the stock low pressure setting, I don't get any ice or snow on the accumulator. It will be dripping wet and just a tiny teeny bit of frost on there. But no ice. No insulation fluff on the accumulator either.
Fun stuff.
Last edited by Reid Fleming; 10-08-2009 at 09:13 PM.
When I went to automotive air conditioning repair school, the "general" specification for system effeciency was air 30* cooler than the ambient temp's. Getting nearly 60* cooler is damn impressive!
When I went to automotive air conditioning repair school, the "general" specification for system effeciency was air 30* cooler than the ambient temp's. Getting nearly 60* cooler is damn impressive!
30° delta temps may be fine for northern climates. But in Arizona when it's 115° outside, I sure as heck don't want 85° air coming out the ducts. That 30° figure probably represents inside cabin temps. Most cars run around 80° inside during the summer with A/C running. That would mean a 50° duct temp or better.
I prefer low low LOW temperatures in order to increase the dehumidification aspect. (More important in humid areas of course)
You are probably correct on it being the cabin temp not ambien temps. I went to A/C school in 03' and have been out of the air force since 06' which was when my being a mechanic for someone else ended and I know work in the medical field so my automotive knowledge has kind of laxed on me.
You can buy Autofrost at the above place. Yes, you need the EPA 609 card. Price of the stuff is pretty good. Cheaper than R-12. As long as you're not leaking, the system will run for a long time. Autofrost has the same long life span as R-12 and mineral oil.
As far as retrofit kits go, there's not much to retrofit. A "kit" is an R-12 style can tap, the refrigerant, a sticker, and some unique service port caps. The unique service port caps have an R-12 connection on top. It's just that they're a different colour than the original service cap already on our cars. Personally, I would use a different R-12 can tap than the one in their kit. I use this one:
As far as switching from Freeze12 to Autofrost, it really depends on what oil you're running. Freeze12 says it works fine in mineral oil or POE oil. But Freeze12 also recommends switching to POE oil for best results......Since Freeze12 is 80% R-134a, I can't see it working too well in mineral oil at all.
Autofrost works great in mineral oil. In fact it's designed specifically for mineral oil. It "will" run in POE. But long life is not guaranteed. POE oil will thin out over time when combined with Autofrost......Do not run it in PAG oil or else your A/C will be dead in less than a month. As a matter of fact, don't run anything with HCFC in PAG oil or else you'll have a dead A/C system.
For you R-134a people, your best bet is to get a can of Tune Air from Cryo Chem and put it in your system. It's a 4 oz can, so shouldn't be a problem of overcharging. If you combine it with their Cryo-Seal, you'll have colder air and be great as far as stopping potential future leaks as well as current leaks. Tune Air and Cryo-Seal are compatible with Autofrost as well.
Simply adding Tune Air to an R-134a system can give you 7-9°F colder duct temps than what you currently have.
Last edited by Reid Fleming; 10-11-2009 at 07:30 PM.
It works great doesn't it?
.......At that point, I pulled over and popped the hood. Who wants a slushy? 
