DigDug

Wow, this I-12a stuff really works! Finally, freezing cold air!

Here are some things I noted while charging my system:

The R134a conversion decal under my hood says 2lb refrigerant, 8oz oil. This differs from the FSM, which says the 93 system holds 16-19oz of 134a (I thought there was only one system in 93, but I can't be sure). Also, back when I first charged it with 134a, the system was clearly overcharged when I tried to put 32oz in there. I reached the prescribed pressures after about 18oz. I dunno.

About 2oz of oil came out when I vented the existing 134a (into a measuring cup with a towel over it to keep the oil from spraying out of the cup). The drier, however, was bone dry. Nothing came out of there at all. I used one of those oil testers afterwards, and it showed plenty of oil, no surprise there.

My system reached correct pressures after charging one 6oz can of I-12a into a hard vacuum. Idling at 2000RPM, stabilized, full fan recirc AC with doors open. Ambient 86F, humidity around 80%. Charged slowly as a liquid as directed by ES. Sprayed the condensor with water a couple times when pressures got up where I wanted them, and they dropped enough to keep charging. Just as I finished the can, I sprayed the condensor again and pressures dropped to right where I wanted them. Ended up about 30-35 low, 190-200 high.

DigDug

Oh yeah, did I mention FREEZING COLD AIR?

After suffering with 134a for over a year now, I'm VERY happy with this stuff.

katit

iTrader: (1)

So, you used just 1 can?

I'm intrigued I did full conversion with flush and oil replacement to PAG and AC works OK but not freezing. I can try this ES-12 just as expiriment and see how it works.

DigDug

Yep, a single 6oz can of industrial 12a. I ran 134a for more than a year and it was cool at best. If it was 90F or higher out, it couldn't even get cool - just warm air like the AC wasn't running. I'm very happy with the ES stuff, it's better in every way.

RX794

Has anyone ever converted from R12 to R134 with 1995+ FD Components? I'm asking because I know that the 1995+ r134 a/c system is completely different, wondering if anyone has ever tried this.

Monkman33

iTrader: (28)

I have a 95 FD and am wondering if I should even bother with converting to I-12a? I know my system is r-134a right now, but with 115 degree summers, I would like to have the best possible air conditioning I can get.

DigDug

FYI, if anybody's looking for a cheap electric AC vacuum pump, I'm selling one here:

https://www.rx7club.com/showthread.php?t=678445

wardaj

Awesome thread! Now I have some of my own questions!
My car was missing A/C when I got it. I will have to plumb the connection from the dryer to condenser myself. I will also plumb the connection from the cross tube ( small one with pressure switch) to dryer. Everythying else I have stock. It was basically missing the connection to/from dryer. If using ES-12 can a generic dryer be used? What about high pressure flexible line such as nylon braided or hydraulic line? Thanks!

M104-AMG

iTrader: (8)

I can't seem to find a temperature vs. pressure chart for ES-12 for both low and highside pressures.

Anyone ?

:-) neil

SaabGuy

I just finished installing AC back in my FC after the car probably not having it for years. I accumulated everything but the evaporator and piced it all together from scrapyards and people from this forum. I renewed all orings using Autozone AC Repait kits, replacing all that I could.


Sucked the system down, checking for leaks and such. Then I loaded freeze12 stuff.

Freeze12 supplies
1 can oil
1 can stop leak
2 cans freon ( I bought 3 but the guage hit 50psi low side after 2 cans so I stopped adding)

So now I've been going for about a month on Freeze12 using old AC parts probably not even used for service in years. The other day on my way home from work it was over 90F degrees outside and my vent temp was dipping below 40F degrees on the highway. Lowest vent temp I've seen so far was 34 degree in about 75 degree ambient outside. BTW road surface temps here in Atlanta run upwards of 150F as measured by my heat gun.

+1 for freeze12 in an old school r12 system

DigDug

The PT chart won't have high and low side values, but the ES-12a does have a two-column chart:

http://autorefrigerants.com/es_chart.htm

If you don't know how to read a two-column chart, read this:

http://www.refrigerants.com/chart.htm

I-12a has a single-column chart here:

http://www.es-refrigerants.com/produ...nt/details.asp

M104-AMG

iTrader: (8)

So where is the "Dew" and "Bubble" pressure's measured ? I'm assuming low-side ?

If so, then according to the ES-12 chart, at 86-F ambient temperature, I should have a low-side reading of 92-psi (bubble/liquid) or 73-psi (dew/vapor) at approx. 2500 RPM on our FD RX7's ?

If so, do I keep filling the low-side with ES-12 in liquid form (can upside down) until I see a stabilized pressure of 73-psi (vapor) ?

The reason I ask, is that I filled with the recommended 2-cans of ES-12, and while the system gets cold at speed, it doesn't in stop-n-go traffic (little airflow), and I wasn't too sure if it's because of just the airflow OR that I have too little refrigerant. I definitely don't want to over-fill.

BTW: at 2500 RPM at 86-F, my low-side is approx 43-psi and high-side is 260-psi, stabilized.

TIA,
:-) neil

DigDug

I'd read pressures at 2000RPM per the FSM for R12. When I used I-12a to charge mine recently, I just took the low-side pressure range the FSM prescribed for R12 (22-28 PSI), looked up the corresponding temp range in an R12 PT chart (21-28F), and then looked up the pressures for I-12a at those temps to get my target range (about 32-38 PSI). I ended up with low-side 30-35 PSI and high-side 190-200 PSI (varies depending on condensor temp, higher as it heatsoaks). This was at 86F ambient, about 80% humidity.

Yes, charge as a liquid and go SLOW. When you get to your target pressures, spray the condensor with a hose and the pressures will drop some, and keep charging until you get to the target after spraying it - otherwise heatsoak will make the pressures read higher than they will normally be. From the pressures you listed, you're overcharged a bit, which may explain why it's not that cold unless you're driving it. Looking at the ES-12a PT chart, your low-side should be lower than mine, probably around 20 PSI. You can vent some without redoing the evacuation - just leave the service hose open and open the low-side valve a little.

M104-AMG

iTrader: (8)

I talked with an Enviro-safe technician, and he said for a 1993 RX7, charge to 40-psi / low-side AT IDLE, even at 86-F ambient.

The ES-12 temp/pressure chart is ONLY if you have equipment that can read the temperature of the refrigerant INSIDE the low-side.

I thought that by waiting 5-10 minutes, the low-side refrigerant temperature would stabilize to ambient . . .

Hmmm. . . .

:-) neil

DigDug

Well, 40 PSI at IDLE may in fact be right - get to that reading, and then rev the engine up to 2000RPM, and you'll see the low-side pressure drop significantly. That may put you down to below 30 PSI, which makes a lot more sense. But 40 PSI at 2000RPM is too high unless the condensor is heatsoaked. If you spray water on it after it's been sitting, you can watch the pressure drop on the gauge.

And you don't need to measure the temps inside the evaporator for a PT chart to be useful.

TypeFD

iTrader: (1)

Is the system considered /open/ if the shrader valve has been removed and momentarily replaced with a new one due to leaking, on a retrofitted r134a system? If so, I assume charging under vacuum is critical (?).

Pulled out all of the r134a refrigerant out today at a local a/c shop. Plan on getting some of that ES12 refrigerant to refill with. Is screwing around with the idle necessary or can it simply be charged to 40psi low-side at idle, 86F amb - straight from a can?

Thanks in advance

-d

M104-AMG

iTrader: (8)

This is exactly what the tech at Enviro-safe recommended.

:-) neil

TypeFD

iTrader: (1)

Wanted to post follow up... I got the i12a from ES, just about 2 cans in and I was floored. This stuff is freezing. I don't remember my FD ever being that cold, wholly crap! Down here in Florida heat stop and go traffic it performed real well...

Those of you wanting cold air, don't waste time on anything else. Go to envirosafe, get 2 cans of the Industrial 12a refrigerant, evacuate your system, and dump this stuff in (assuming nothing else is broken).

This is too good to be true... I hope it lasts.

DigDug

What were the pressures after adding 2 cans? At what idle speed? And what year is your car? I'm interested because I only needed a single can to charge mine, but there were 3 different AC systems in FDs IIRC. I think for 93 there were both factory- and port-installed, but I might have that mixed up with another year. Mine is a 93 (originally R12), and I think it's a Nippondenso.

TypeFD

iTrader: (1)

44 psi. It's a 93 Touring. Nippon Denso. Actually, my system took about 1 1/2 cans due to improper fitment on the first can which caused some of the refrigerant to vent. Second one came in real smooth but not all of it. So it's definitely less than 2.

I noticed that to achieve 44psi FD must be completely cold (I did it in the morning after letting it sit overnight). I also sprayed condensor down with water to help get the pressure. The idle was about 1,200rpm (cold) initially, then settled to ~750rpm by the time I hit 44psi. Once I hit the mark, I turned the car off, closed the valve on the can and pulled it off - noticed that it still had a little bit in there, which I figured I could always add if need be in the future.

Now, how does your A/C perform now? If it blows cold and operational I wouldn't worry too much about amount of refrigerant in this case. Besides, undercharging is not going to hurt your system, overcharging will. So if it blows cold and everything seems normal (load/idle... etc) I wouldn't worry too much over 1 can of charge.

Can anyone else chime in on this?

P.S. To be sure on the kind of system you have, inspect your receiver/dryer. MANA is black and has a mounting bracket welded to it. Nippon Denso is aluminum and has a wrap-around bracket. I've also read on the forum that you can register you FD (VIN) with www.mazdausa.com and they'll be able to tell you everything your car has.

DigDug

Mine is freezing cold. Never had to turn down the AC before switching to I12a.

I'm not worried about the amount in my car. Just wondering how much others used since there were different systems over the years, and mine never seemed to hold as much as others said it should. The operating pressures are perfect on both sides for mine - 30-35 low, 190-200 high at 2000RPM. Around 40PSI low-side may be right at low idle, but the high-side at that speed should be lower than 200. Did you use a manifold gauge?

pinkrx7

iTrader: (2)

Sorry to bring this thread back from the dead but I found a really great price on driers for our cars.
http://www.caawparts.com/index.asp?P...APAAID=1192485

10 bucks just call in.

danny hahn

I have to do a write up from last July.

Dave Newbern gave me the hook up! He had various fittings, o-rings, etc. Which were essential for being able to hold pressure for many minutes (maybe 20?).

Vacuuming the system while the car was hot was the way to go. Apparently there is a water vaporization point (I think 32 in-Hg?) that we were able to barely exceed with the Harbor Freight Vacuum box.

My Tig welded repaired line has worked wonderfully. As my sight glass is still full.

He also had various can attachments for adding the coolant. We used one can of regular and one can with dye.

A/C works wonderfully at speeds 3 1/2. I have a PFC which causes the A/C switch to work intermittently. So I will eventually get around to that fix.

Thanks again Dave!

katit

iTrader: (1)

Checked their website - 2 cans ending up costing $40 because of Hazmat fee..

NewbernD

iTrader: (1)

You're welcome. Glad to hear you found a setting that allows it to work. I forgot all about the PFC/AC switch problem when you were over.