Since I bought my 1990 Bronco in 1999, I have never had A/C. I've been looking into getting it recharged with R-12, doing the R-134a conversion on the cheap (just adding refrigerant and oil) and also getting the R-134a retrofit done right (new accumulator/dryer, seals, remove at least 98% of mineral oil, correct compressor, etc). After exhaustive research, I couldn't find a good solution.

Just a word of warning to those who put R-134a into an R-12 system: it will work, no doubt. However, R-134a and R-12 do not use compatible oils. R-12 needs a mineral oil, R-134a needs ester/PAG oil. The different oils do not dissolve in the refrigerant. This is extremely important to the longevity of the system. The oil is not only designed to lubricate the compressor, but also to seal and condition the hoses, seals, etc throughout the system. As little as 2% of mineral oil left in an R-134a retrofitted system can cause eventual failures of seals/compressor, etc.

This sucks, I know, because it means there is no easy, cheap way to permanently fix the A/C. The solution I found came from one of the Enginemen who work for me in the Navy. He told me to go to:

http://www.epatest.com

You can take the EPA's 609 MVAC (Motor Vehicle A/C) certification course online for $19.95. They have an online study guide. All you need is about 1.5 hours to study the 25 page study guide and correctly answer 20 of 25 multiple choice questions correctly. Then you will be certified to purchase ANY refrigerant for small vehicle use (not large bus A/Cs, but passenger cars) so long as you are purchasing less then 20lbs at a time.
You can find R-12 and other alternative refrigerants in 9.6oz and 12oz cans at:

http://www.refrigerantsales.com

The best part about it is A/C really isn't too hard to do, and it's good money on the side. I have purchased a set of R-12 manifold gauges ($49.99) and a compressor run vacuum pump (29.99) from:

http://www.mvpro.com

I found a portable R-12 reclamation unit for $175.00 on Ebay (you only need this if you plan on doing 609 work for hire. Otherwise it is cheaper to take the vehicle to a shop and have them reclaim your refrigerant. NEVERY VENT R-12 INTO THE ATMOSPHERE. IT'S NOT WORTH THE FINE!).

R-12 is very expensive to purchase because it can no longer be manufactured, so whatever is left on hand from recycling is all the shops have. If you take your car in, the shop with simply "clean up" your existing refrigerant and put it back in.

I have been using a product called AutoFrost (GHG R406a). It is about the best R-12 replacement on the market. There is no such thing as a "drop in" replacement for R-12 because no matter how compatible it is with the system, the EPA requires that new placards be placed on the vehicle and specific fitting used with each type of refrigerant be installed. They are easy to get and usually come with any shipment of refrigerant.

AutoFrost is:
55% R-22 (the refrigerant used many homes. It is a CFC like R-12)
41% R-142b
4% R-600a (Isobutane)

The refrigerant is certified by the EPA to be non-reactive/low flammability (due to the Isobutane). In it's current mixture, it is non-flammable (most refrigerants, like R-12 and R-134a, are not flammable). For lots of tech info on AutoFrost go to:

http://www.autofrost.com

Here are the results of the flammability testing:

http://www.autofrost.com/monroe/safety/safety.html

AutoFrost is completely compatible with the R-12 mineral oil, seals and compressor. What’s better is it runs as pressures almost identical to R-12. R-134a can be damaging to R-12 systems over time due to the higher pressures it runs.

I have done a dozen or so A/C retrofit/rebuilds in the past couple of months. I will stand by AutoFrost as being a very good, inexpensive alternative to R-12. R-12 is $250.00/case 12 cans Vs $95.00/case of 12 cans AutoFrost. You can buy the cans individually.

The vehicles I have retrofitted to AutoFrost (including my Bronco and 1989 Volvo 740 Turbo) all show vent temps of no more then 38 degrees with 85 degree ambient and 90% humidity. My Bronco was at 29 degrees last night and it was still 80 degrees with 90% humidity in VA. The R-12 recharges haven’t shown as good of numbers.

I can email anyone interested in the specific steps I went through and the individual costs involved for the Bronco retrofit. It's worth the investment, and if you do just one or two of your buddies trucks on the side, the equipment more then pays for itself.

 

I have been using that Autofrost R-406 for three years now in my car and truck. I have not had any problems with it and the air temperature is a bit colder than it was with R-12. I have retrofitted several commercial ice machines and sandwich coolers with it and it works very well.

 

Great post!! This is exactly the info I've been looking for. I also own a Bronco and would love to hear from you regarding your specific steps and procedure. However, I can't contact you via email thru this forum because I haven't yet met the minimum number of posts to qualify. I would give you my email addy now, but I don't know if that would be in violation or not. Maybe some of the FTE veterans have a solution for this. I have learned so much on this forum, thanks to posts such as yours!
OldVanRiver

 

After you reclaim the R-12 from someone's system, what do you plan on doing with it then? If you convert them to autofrost, then you are stuck with paying to dispose of the R-12. If you plan on using the R-12 again, how can you be sure it is not contaminated by someone who put the wrong refrigerant in that system or other oil or dye? I was under the impression that it is very difficult to identify a refrigerant that is pulled from a system with an unknown history(no paperwork). This whole business seems too complicated.

 

P.S. You mentioned a temp of 29F at the vent? If that is true you are running too cold, wouldn't the evaporator freeze up and fail to dehumidify the cab and dramatically cease to cool the cab?
That is alot of R22 which has a boiling point of about minus 90F or something close to that. What will happen in the winter when it is time to defrost the windshield?