Putting propane in R12 ac system?

[4570Man]

If it just seems like a bad idea to you please go away. If there’s an actual safety concern based on fact, voice your concerns. Next question will it actually work? I’ve got a 1992 truck with an r12 ac system. I already tried charging with 134 and it didn’t work very good and currently doesn’t work at all. Maybe the not working at all was unrelated but it still only cooled to like 55 degrees out the vents. It was better than not having it but not very chilly either. If the propane did work would it be an improvement?

 

[CADplans]

The temp drop across the evaporator coil is more important than some specific number,, like 55 degrees,,

If you actually get a 30 degree F drop,, the system is perfect,,
a 1992 truck, with the wrong refrigerant,, I would be ecstatic with 20 degrees drop.

I am not quoting actual numbers, but, a different way of evaluating if the AC is working,,
Temperature drop,, not some number,,

The cooler the incoming air, the cooler the delivered air,,

My 2018 truck seems as though the AC is broken of the windows are down,,
because the air entering the AC is hot,,,

roll up the windows,, 5 minutes later, the AC seems to be like a walk in freezer,,

 

[4570Man]

If I could maintain 20 degrees cooler I’d be thrilled. But if it can’t beat the windows down than it’s pretty useless. Currently it doesn’t work at all. I haven’t determined if it’s a wiring issue or a bad compressor.

 

[Diggin It]

I'd be concerned about the potential Kaboom.

 

[4570Man]

I'd be concerned about the potential Kaboom.

If my 2 pound system of propane is hazardous you better start a campaign to ban propane and natural gas vehicle. Not that gasoline is much if any better.

 

[Industrial Toys]

Maybe it's just a matter of the propane then being part of the air circulation system. I drove two Propane cars for years. Propane sinks which isn't that big a deal in a vehicle and stinks pretty good to give you a heads up warning of a leak.

 

[Gary Fowler]

You need enough pressure in the system to convert the gas propane back to liquid for it to work as a refrigerant. According to Google search that is 177 PSI @ 100F. The pressure would be less at a lower temp but I doubt you AC compressor is up to the task even at 80F.

 

[kf4uda]

I have never heard of charging an AC system with propane. Just out of curiosity, where did you come up with the idea to do so? I am always up for learning something.

 

[4570Man]

I have never heard of charging an AC system with propane. Just out of curiosity, where did you come up with the idea to do so? I am always up for learning something.

I’ve heard of it being done before after doing some reading it’s apparently a good refrigerant and not that uncommon in commercial coolers.

 

[RickB]

You need enough pressure in the system to convert the gas propane back to liquid for it to work as a refrigerant. According to Google search that is 177 PSI @ 100F. The pressure would be less at a lower temp but I doubt you AC compressor is up to the task even at 80F.

If his compressor cannot develop 177 psi that is a problem in itself.

 

[4570Man]

They’re supposed to be around 200-250.

 

[RickB]

They’re supposed to be around 200-250.

Exactly. R134 systems can be higher.

 

[LouNY]

It works.
Not much more to say about it, it's also common in the rest of the world.
It's called R290.

 

[LouNY]

If it just seems like a bad idea to you please go away. If there痴 an actual safety concern based on fact, voice your concerns. Next question will it actually work? I致e got a 1992 truck with an r12 ac system. I already tried charging with 134 and it didn稚 work very good and currently doesn稚 work at all. Maybe the not working at all was unrelated but it still only cooled to like 55 degrees out the vents. It was better than not having it but not very chilly either. If the propane did work would it be an improvement?

Did you change out your oil with the 134?
If you didn't mix the oil and it has enough of the old mineral oil, go with the propane.
If the 134 you added had oil in it you need to flush out the system.

 

[sandman2234]

Have you considered just putting R12 back in it?
David from jax

 

[4570Man]

Yes I added oil when I put the 134 in. As to the R12 it’s hard to get and expensive. Remember it’s been banned since like 1994. All that’s left is old stock and reclaimed.

 

[Tractor Seabee]

Propane has been used many times in the past. It never caught on in the US mostly foreign countries. There is a lot of thermodynamic engineering goes into matching components with the refrigerant. There are many variables in the math. Compressor volume-metrics and horsepower requirements to drive the compressor being a couple. If your info is right on the propane pressure/temperature relationship; if propane actually liquefies at 150# and 100 degree condensing temp it is between R-12 and R-22. Compressors were interchangeable between the two depending on application. That ignores the rest of the equation though. LOL, I would get more info before trying.

Several of the new replacement refrigerants are both flammable and anesthetics. Over time many of the fuel gases have been tried but did not catch on for various reasons or till something better came along.

R-12 replaced sulfur dioxide and methyl chloride. I started in that trade just as that change was being made. Both of those were nasty stuff. Marine systems have used CO2 for years but take massive compressors and steel pipe due to the high pressures developed. I worked on a few of those. Don't overlook R-717 (ammonia). That has been around since the 1800s and still going strong, systems being installed every day. For commercial and industrial uses it is still preferred.

Changing from R-12 to R134 is relative simple depending on what the liquid metering system is. Some are adjustable, most are fixed. All of the old oil has to be drained and the system flushed to get any residue out. Totally different oil requirement. Due to the engineering I discussed earlier the same compressor and drive will provide heat extraction than with R-12 ; so reduced performance is expected. I have not researched or have a need to on whether a new pulley is available to overcome the difference.

Refrigeration 101.

Ron

 

[Tx Jim]

If my 2 pound system of propane is hazardous you better start a campaign to ban propane and natural gas vehicle. Not that gasoline is much if any better.

Several yrs back my neighbor put Propane in air conditioning systems on several trucks/tractors/combines. He was instructed by some local authorities to cease installing Propane in AC systems or legal action would be taken. YMMV I think you're doing something incorrect when installing 134A because my JD 4255 AC cools as good or better on 134A than it ever did on R12. I'll bet you installed too much 134A!!

 

[fried1765]

If it just seems like a bad idea to you please go away. If there痴 an actual safety concern based on fact, voice your concerns. Next question will it actually work? I致e got a 1992 truck with an r12 ac system. I already tried charging with 134 and it didn稚 work very good and currently doesn稚 work at all. Maybe the not working at all was unrelated but it still only cooled to like 55 degrees out the vents. It was better than not having it but not very chilly either. If the propane did work would it be an improvement?

You just reminded me: I have a 20lb.(?) tank of R12 that I need to put on E-bay and sell.

 

[TractorGuy]

I think you're doing something incorrect when installing 134A because my JD 4255 AC cools as good or better on 134A than it ever did on R12. I'll bet you installed too much 134A!!

This is a good possibility. You don't want the same pressure you saw with R12. On my backhoe anything over two cans results in reduced cooling and higher pressures. The sight glass on the drier never comes close to being clear. I flushed it out completely and installed a brand new compressor, drier, and expansion valve. It cools okay for being a glass oven. Much like your old truck.

Here is a conversion chart that you may find helpful.

I don't see a 55* vent as being too bad depending on outside temperature. Just looking at the vent temperature without considering the outside temperature and humidity doesn't tell much.


I did some conversions back in the 80s by just flushing and refilling with ester oil and 134A. The systems I was working on were never known for great cooling to start with so performance wise it worked okay. The biggest problem I saw was compressor seal leakage from the old York compressors that were not built to use R134A.

If I were retrofitting an old vehicle today I would go ahead and get a Sanyo compressor with a compatible drier and expansion valve or orifice tube.