Hi,

Just wanted to get some opinions on my A/C conversion.
My A/C originally ran on R12 and I converted it to R134a about a year or so. Never liked the performance of R134a in a R12 System. It works well in systems designed to use it but not in most R12 systems.

Especially idle performance remarkabely suffered.

I followed the hydrocarbon refrigerant discussion in several forums and decided to give it a try. I know it is not approved in the US as HC are flammable but so is the new R1234yf refrigerant. (Mercedes already stopped using it as it will turn into highly corrosive fumes when burning ( hydrogen fluoride acid), so corrosive it will eat glass and turn it milky.)

I am from Germany where HC refrigerants are common in almost every refrigerator, freezer and some A/C systems. Of course it is flammable, but there are millions of Australians using it in in MVAC systems and I have yet to hear a single fire caused by HC as refrigerant, domestically and in MVAC.


So I got myself a bottle of R600a (Iso-butane, NOT regular butane! ) and R290 a form of refined propane. Both environmentally friendly, non toxic refrigerants that are available over the counter overhere.

I got rid of the malperforming R134a and installed a mixture of roughly 50% R290 and 50% R600a and adjusted the Low pressure cutout slightly due to the lower overall pressures in the system now.
You only fill 30-40% of the R12 and fill by weight. So around 300 - 350g is all you need to fill the system.

And the result:


What a huge difference! Ice cold as with R12 (mid-high 30s vent temp.), lower high and low side pressures than R134a, compressor very silent and cut in way less noticable. Less drag I would assume too.

Overall a great success. No need to change orifices, oil or dryer as HC are non corrosive and work fine with mineral oil as R12 did.


Now lets hear some opinions!
(Again, no need to tell me it is flammable, so are the 15 gallons of fuel flushing at 40 PSI throgh lines next to the headers)

 

Interesting solution hope it works well for you.

I have been using ES12A for R12 conversions with excellent results. Vent temps are colder than R12.

 

You are basically using the same stuff as I do.
ES-12a is also a HC refrigerant, most likely made of the same ingredients. No wonder yours works so well!

All those 12a stuff is basically a mixture of hydro carbons, mostly refrigerant grade propane and iso butane.

 

I have an 89 with the R12 system that has never been converted to 134a. Is there anything I need to do to run this? Or just change? I had an O ring leak and need to recharge anyhow and the R12 is hard to come by now...

Churchkey how are the long term results with this?

Daniel

 

No need to change anything! In fact the best start is a R12 system that has never seen R134a and is original with no leaks.

You have to make sure the system is leak free! Especially the evaporator so no refrigerant can leak into the cabin and start a fire.

HC refrigerants will leak slower than R134a in a R12 system because of the larger molecules of propane and iso-butane compared to R134a.
The old hoses and O rings will let R134a pass through easier because they do not have the nylon barrier as R134a hoses will. So a "leaky" R134a conversion may be fine with HC. But pull a vacuum to be sure you have no leak before putting in HC refrigerants anyway.

And remember, you will only need a third compared to R12/R134a so do not overfill!

 

But anyone in the US please check your local laws and decide yourself if you want to use HC refrigerant. As far as I know the EPA does not like them.

Oh and better don´t smoke while charging your A/C...

I will be changing a slightly leaky schrader valve soon and therefore have to refill the system again. Maybe I will make a how-to video if I find the time.

 

Nice! I know where the leak is but I will change the O ring and vac down for sure before hand. The car sees lots of HPDE time and the temps are high so that is something I DO NOT need to worry about!

Daniel

 

Have been using it in customer cars for a # of years without issue.

On a personal note, put it in the wife's XJS 2-3 years ago after a compressor & dryer change = A OK.

 

To change from R12 to R134A you need to get new hoses made, the gas particles are smaller and will leak heaps and tear into the old hoses.
Drain the old oil out of the compressor and replace with the synthetic stuff fit a new orifice tube, replace all the o rings evacuate the system and charge to 80% of the R12 weight.

I did mine many summers ago, she blows ice cold and have not had to touch it at all since.

I would not risk flammable / toxic blends, if it leaks you will inhale it. If enough leaked while parked and resulted in an explosion when you went to start the car, how will the insurance cover it?!?!?

 

I just did a R134a drop in back then and I agree, with a proper conversion R134a may have worked better than it did.

But you will not get the same performance as R12 in most systems because in R134a systems the compressor is somewhat different and the condenser is more efficient or larger to make up for R134a´s lower thermal efficiency compared to R12.

As you said, hoses, oil and o rings will also need to be changed to do it right.

Those R134a conversion kits that just make you add the oil and the refrigerant are junk.

 

There is no risk through inhalation from R290/R600a they are 100% non toxic. The only risk is because they are flammable of course. But so is fuel and brake fluid. A couple of ounces propane and isobutane are negligible AS LONG AS they do not leak into the cabin of course.


R134a has a toxicity when inhaled btw, and is also flammable in combination with the refrigerant oil. Autoignition point is also lower. And if R134a gets near a heat source it decomposes into very toxic fumes such as hydrofluoric acid ( same as with R1234yf)

I will still use R134a in my other vehicles because no refrigerant is 100% safe, they all have their pros and cons.