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-   -   Converting vehicle A/C from R134A to propane? (https://ecorenovator.org/forum/showthread.php?t=6652)

AirConditioner 05-06-18 11:38 PM

Converting vehicle A/C from R134A to propane?
 
I have a 1998 Jeep and the air conditioning has a very slow leak. It's not a big deal, I only have to top it off about every 6 months. With that said, I'm interested in converting it to use propane refrigerant instead of R134A. I know that propane works at lower pressures and is more efficient/colder than R134A, and is a common replacement in older vehicles that came from the factory with R12. I strongly dislike R134A due to it's higher pressures and rather poor performance. Propane is also cheaper to keep topping off.

I've been searching google on this topic and I can't find a lot of information regarding converting R134A vehicles, it's all about older R12 systems. (probably just because you can't get R12 anymore)

I'm wondering if it would be OK to convert the 134A system to propane without any modifications? Would the thermal expansion valve still operate in an acceptable range? Would there be any problems with compatibility of the oil in the system, or the compressor itself?

NiHaoMike 05-07-18 08:23 PM

R290 operates at higher pressures. You want some mix of R290 and R600a. Or just use R152a, commonly found as duster cans.

jeff5may 05-09-18 11:45 PM

Propane and butane mixture works well.

AirConditioner 05-11-18 08:27 PM

That's interesting...I thought 134A wasn't a very efficient refrigerant because it was higher pressure. Will a propane/butane mix provide better cooling? Can I simply vacuum and charge the system with it, without making any other changes?

oil pan 4 05-12-18 07:18 AM

I think the hydrocarbon replacement for R-12 is called freeze12.

AirConditioner 05-12-18 07:00 PM

Quote:

Originally Posted by oil pan 4 (Post 59133)
I think the hydrocarbon replacement for R-12 is called freeze12.

I'm not asking anything about R12.

NiHaoMike 05-12-18 10:13 PM

I really think R152a would be your best bet. No need to get the mixture right, just put a can tap on a duster can and put it in the low side until the subcooling is what you expect.

jeff5may 05-13-18 08:21 AM

The aftermarket natural refrigerant blends are a precision blend of propane and isobutane. Isobutane has a boiling point of around -10 degC where natural butane has a boiling point around 0 degC at sea level. Propane has a boiling point around -40 degC. What this means for the conversation here is that both types of butane do not develop enough vapor pressure compared to r134a, and propane develops too much vapor pressure. The care line of refrigerant is either a blend or pure propane isobutane. Care 30 is closest to r12 or 134 and is about half and half of each.

oil pan 4 05-13-18 09:14 AM

R134a is the replacement for R-12.
A product called freeze12 is a propane blend drop in replacement for R12, it should also work for replacement of R-134a.

Jeff explained how we need R-12, R-134a and propane blends to achieve certain pressures as they phase change.

Straight propane would be more like trying to replace R-22 or R-410a. If either one of these were used in an automotive A/C it would break something because the pressures would be way too high.

jeff5may 05-13-18 09:22 AM

2 Attachment(s)
Here's some info on r152a. It was recommended by the EPA over r134a during the r12 phase out process. As a drop in replacement, you will lose a little capacity versus r134a. Maybe 10 percent.

Check out the graphs and this article:
https://www.kth.se/itm/inst/energite...del-1-1.686423

If you're looking for quick and simple, the r152a is a single substance. Since you have a leak, using a mixture is sketchy because the more volatile substance (propane in this case) will boil off first whenever it can. Also, since isobutane has a boiling point around freezing, when the mixture becomes mostly butane, you could end up sucking air into the low side if that's where the leak is. With decreasing mass in the loop comes decreasing suction pressure, so at a certain amount of leakage, the evaporator circuit will be operating well below atmosphere.

oil pan 4 05-13-18 06:06 PM

If I remember correctly 152 is "computer duster".
It's been around for a long time and there's no patient on it, and it's cheap.

What's it need for lube?
Ester based or mineral oil base?

I use it as part of a mix to fill trailer tires.

jeff5may 05-18-18 10:47 AM

As far as compatibility goes, propane and butane don't care. They work with natural and synthetic lubricant just fine. R152a is very similar to r134a, so it likes synthetic oil better than natural, just like r134a.

elhigh 05-24-18 03:09 PM

I know I'm weighing in a little late on this, but have you determined the location of the leak? If it's your hoses you may just need new O-rings. Cheap fix, quick, recharge the refrigerant and be done for years instead of months.

ham789 06-12-18 08:02 PM

R134 leaks
 
As it was explained to me...
The R134A molecule is VERY MUCH SMALLER than the molecule
for R12. It leaks out thru the hoses because they are too porous
to contain it. That's why you can't just put R134A in a system
not designed for it. Maybe you can replace all the flexible hoses...dunno.

Compare the cost of just adding more at intervals to your other
options. May not be such a bad idea to keep what you've got.

WyrTwister 06-13-18 08:00 AM

I have read that old hoses used on R12 have absorbed enough oil or something , to make them less porous . Enough to work OK .

Wyr
God bless

Themitchells04 07-09-18 04:59 PM

I have successfully used propane in a r12 car system. I tried to put propane in a 134 a system never got the compressor to kick on May have had other problems with the system but I gave up and never tried again. Would also be interested to see if anyone else had luck With propane .

dc€x 09-11-18 03:50 AM

One labstudy on r134 "drop-ins" also available from Spain.

https://www.researchgate.net/publica...a_alternatives

The indicated pressures (MPa) in the test are probably misleading (bar OK?).

However ,its obvious r290 and r152a superior to r134a and ... to newcomer r1234yf, which is (of utmost peculiar reasons) chosen as the winner refrigerant over r134a in the new car segment.

Earlier for ex. VW-was stronly against r1234yf but today the very same refrigerant is
as a default in their new vehicles ... odd!

https://refrigeranthq.com/germany-au...gainst-1234yf/

Vikijoj 09-18-20 02:05 AM

]

There are not enough information about your question , and there are many miss information out there because r290 is flammable and industry doesn't like to use it in cars . And also it is not legal in many places to use R290 or R600a in cars . Also it is illegal for neutral person in many places to buy r134a gas . And that attract them to use Potentially explosive gases . So if you want to experiment Try on your own risk .
To do such conversation the best mixture would be 10% r600a and 90% r290a or , 10% r600a 40% r290 and 40% r134a . Of course first mixture has better performance . Second mixture reduce The flammability.
As a compatibility , There is 2 issues ,first is compressor oil , which needs to be thickened , for example pag oil 46 should be replaced by pag 100 . To provide correct lubrication ( on this on There is good research , you may find it ) . The second is refill volume , which should be 40% of r134a . For example if your system requires 500 gram of r134a refrigerant , you shouldn't fill it more than 200 gram of r290 .
The procedure of refilling should include complete vacuum of system , hoses and gauges . Since it is legal to release R290 or r600a into atmosphere in many countries , prefilling of system with r600a and vacuum it and then complete refilling with mixture of R600a and r290 to ensure zero presence of Oxygen in the system .
All and all r290a is explosive and is used in many house appliances like fridges and indor air conditioners , with possibility of leaking in closed spaces and creat big enough devastating explosions. But we do not hear such stories everyday . Maybe when car industry move toward r290a , law would move toward legalisation too .
As a comparison r290 is superior compaire to R134a performance , reducing electricity or fuel consumption , compatible with all oils , ozon friendly (actually one of the lowest ozone depletion potential refrigerants) . But again , explosive property of it makes it more deficult to use and service . Specialty in cars which condenser is located where the most of the car crash damage and potential fuel burn is .


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