HC r134a Alternative/General Questions

[BlueBertha]

Howdy, so I'm sure everyone has seen a thread like this a million times, so I'll ask new questions. I just got my a/c system leak checked and all of the r134a pulled from the system by a shop. I am going to replace my discharge hose as it is leaking, and then re-fill the system at home. My a/c has been pretty crappy, as r12 to r134a systems are known for being, and my compressor has a small leak and I pretty sure is on the way out, so I said HEY, I GOT AN IDEA. I came across the 12a "duracool" type HC based refrigerants, which are just refined propane. It's supposed to be more efficient marginally than even r12, I think it's something like 6oz of 12a = 17oz of r12. Anyway, I'm wanting to try it seeing as I have nothing to lose. There are a few things I'd like to know before just jumping in. I know I have heard people say a/c capacity's in lbs, psi, and oz, so I really don't know what to go by. According to my understanding, I simply need to fill my evacuated system to about 40 psi steady. The math I did once said my a/c system holds 33oz ('91 EF Civic) of r12 factory, so in turn I need 12oz 12a "duracool"? Apparently the duracool has higher pressure/more charge in fewer oz? If anyone can explain that to me that would be sick.

Last question is about oil. The shop that emptied my system didn't remove any oil, just the r134a. The duracool can and website says the refrigerant comes with "oil chill", their brand a/c oil. Does this mean I can just recharge without worrying about oil? If I were to replace the compressor myself in the future and recharge with duracool, would I need to add separate pag 46?

I've read many threads about the simplicity of using this stuff, but in my head I'm going through all these details. If anyone has done a HC type refrigerant conversion, I'd love some tips. Thanks

Here's a link to the product: Duracool 12a Refrigerant 6oz Can – Deepfreeze Refrigerants Inc.

[Cornbinder89]

It has been written up on here before, and I wouldn't use it. First question is where do you live? HC refrigerants are not allowed in motor vehicle in the US but are in Canada.
They contain no R12 what so ever as mfg of R12 has been banned. I once looked up the chemical make-up (a look at the MSDS sheet will tell you) and found they are a mix of things often with R134a.
R290 (propane) vapor pressure @32 deg is around 53 psi. closer to R22 pressures.
You can't tell a thing about amount from PSI, capacity or amount is always by weight.
HC refrigerants are legal in this country as replacements for small appliances where the total cap is very low.
What you do is up to you, but in the US your system would be considered "contaminated" and most shops would refuse to connect their equipment to it.
IF you want better cooling out of your converted R134a systems, increase the condenser area. That will be the best money spent, and leave a completely legal system.
It may take some re engineering to fit a bigger condenser or it may take stacking condensers (inlet from the compressor to the rear in the stack, outlet to the evaporator from the front).
Any leaks should be dealt with first, otherwise it is a waste and will add to the GW problem. Do it right, do it once.
I wouldn't have any of those products in anything I own. The dangers of flammable gas in a crash are real.

[Cornbinder89]

IIRC is was propane butane and R134a when I looked it up, I could be wrong as my memory isn't what it used to be.
read about it here esp the part about the death of 18 people due to it:

https://en.wikipedia.org/wiki/HC-12a

[AndrewVanis]

IF you want better cooling out of your converted R134a systems, increase the condenser area. That will be the best money spent, and leave a completely legal system.
It may take some re engineering to fit a bigger condenser or it may take stacking condensers (inlet from the compressor to the rear in the stack, outlet to the evaporator from the front).

Can you please expound on this or direct to post/resources that would cover this? Thanks

[Cornbinder89]

One of the big problems with 134a retro-fits is the surface area of the condenser. It is why we went from big tube and fin condensers to serpentine and today to parallel flow types, each step forward has narrowed the tubes to increase the surface area the refrigerant is exposed too.
When a retro-fit is done, you are trying to use a condenser that was ok for R12 for a different refrigerant. The greater the surface area you can get the better the system will work (within reason). With cars esp those designed for R12 the area allow for the condenser is small. Often it is not possible to fit a bigger condenser in front of the radiator. You may only have 12x 24" or so. Older tube and fin condensers were often thicker overall than parallel flow types. So if you replace a tube and fin with that is over 2' thick with a similar sized parallel flow may be thinner than an inch. This gives the option of "stacking" two units to increase the surface area. Any heat exchanger in such a stack, you want the hottest gas in the rear, because the air passing through the front will heat the air the rear will see. So by making the rear see the hottest gas makes the most sense.
Double stacking will NOT double the capacity of the condenser, but will make it bigger than one single unit alone. Normally the discharge from the compressor would go to the top connection on the rear condenser, the lower connection from the rear would be connected to the upper on the front condenser, and the lower outlet of the front would go to the evaporator.
I have not had to do this YET, I may have one car that now has a marginal serpentine unit, and I may stack a parallel flow units. I have replaced condensers with larger units when converting trucks from R12 to R134a with excellent results, lower head pressures and cooling to the frost limit in 95 deg temps.
When stacking sealing them together so air has to flow through both will be important, as well as sealing the whole condenser assembly to the car and radiator to maximize airflow though the condenser.

[AndrewVanis]

helpful, thank you.