Using Propane as a AC refrigerant

[Warpig Racing]

Any A/c people want to tell me this is a bad idea? Just curious before I find out the hard way why it is a bad idea. I know it doesn't sound safe but my research is saying that it is not a horrible idea. guess its all relative. Propane is a very good refrigereant. Just appears that big business has lobbied congress and made scare tactics to get the use of it banned so they big business can protect their patents and business.

[cgrey8]

I've known people to run propane as an R12 replacement more than a few times. The main danger with running propane as a refrigerant is in a wreck when it can escape in large quantity while metal is scratching against itself and glowing light bulbs are bursting.

The other concerning danger is right after charging the system when you could have a rapid leak you don't yet know about. A rapid leak may leak slow enough to not be detected right away, but leak enough to collect to dangerous levels. Likely ignition sources in this case are when you open the vehicle door, a furnace/water heater lighting up, or any other spark source in proximity with the collected propane. Since propane is heavier than air, it will tend to collect at the floor and won't dissipate easily making it particularly dangerous when leaked in garages or basements. If you do get a leak like this, it'll likely be right after you charge the system.

People using propane for refrigerant was particularly popular in the mid 90s when R12 was banned and R134a conversions were crap. It also helps that propane emulsifies into mineral oil, the same oil that R12 uses. R134a can't use mineral oil and requires ester, POE, or PAG. For R12 conversions, I believe POE is used since POE doesn't react adversely to mineral oil the way ester will. Ester and mineral oil, I've heard, will gel which was the source of why so many early R134a conversions ended with seized compressors.

[Warpig Racing]

Finally an educated reply to my question. open to other ideas...

Can R134A stsyem use the propane if i switch out the oil? Or is that necessary?

[MalcolmV8]

The explosive nature of a flammable gas such as propane is enough to keep me clear of it. It's not worth your life or someone else's life when your vehicle blows up.

[cgrey8]

A lot of the attraction to using Propane was because R12 was so expensive and the R134a conversions were iffy if not done right and thus cost more than recharging R12 systems with R12. And because of the unfamiliarity with R134a, many R134a conversions didn't cool as well as when the system was R12. So when faced with a potential $600 repair bill to recharge R12 or $1000 repair bill to convert to that crappy R134a stuff, using propane was attractive enough to risk. The economics pushed people strapped for cash to rig up an adapter to adapt a propane tank to R12 fittings for maybe $30 in parts and fill the AC system from their charcoal grill's propane tank. Total cost WAY below $100. They tell their buddies about it. Then they start using that same method to fill their systems. Add to that, Propane and R12 live quite nicely together in the same system, so topping-off a weak system with propane was also easy and effective.

But now that R134a conversion kits can be bought for ~$50 at AutoZone and most cars today are already R134a, the cost of just using R134a is much more palatable making the attraction to propane just not worth it. So I don't know that anybody has actually tried to run propane in an R134a system.

Interesting tangent...in the mid 90s, R12 was the most smuggled contraband into the US. It topped pot, cocaine, heroin, and guns combined because the street-value of R12 was just that high. Even though demand for R12 has gradually reduced since the mid 90s, as recent as 2008, I've read Internet articles saying R12 is 3rd most smuggled contraband into the US from Mexico. And guess what it was popularly transported in? Propane tanks. Everything from really large to small propane torch/Coleman stove tanks. When it could be made for less than $1/lb and sold for $60+/lb here, that made it a prime target for the black market. The law said R12 could be sold, but no more could be manufactured or imported. So what we had back in ~1996, whenever that law was enacted, was supposed to be all there was. The theory of the law being the lack of availability would eventually drive people to the R134a conversion. In reality, risky practices with propane and the black market supply of R12 filled the void. I've heard that the majority of the R12 people have today is contraband and was made way after 1996 but since R12 was never marked (like untaxed diesel), there's no way to distinguish R12 made today from R12 made 20 years ago. I don't know if that's true, but I wouldn't doubt it.

[Warpig Racing]

My brother did the conversion to propane the other day. The AC is COLD. We are going to get our cars together and compare who's AC works better. His is 04 Ford Tauras and I have an 05 Camry. I'll keep you posted

[v8ranger]

Thats just crazy in my opinion. Putting something in that could cause an exsplostion just to get it a little cooler is just nuts..... My a/c blows 45 to 50 degrees, thats plenty cold enough.

[Warpig Racing]

There is only like 3 oz or propane in the system. Thats not going to cause a massive explosion. My dodge ram is next

[Warpig Racing]

Compare that to carrying 25 gallons of gas in your tank. So a few ounces of propane doesnt sound so bad???

He made a conversion kit from a cheap propane torch head and a fitting from the hardware store. Said he had $9 in the adapter. That then screws directly into my R134A fill hose on my guage set.

[cgrey8]

Even if you completely fill your system with Propane, that's only 20oz vs multiple gallons of gas you never think 2nd about driving around. It does put things into perspective. But even if you get a fuel leak, you won't have 20oz of gasoline immediately gassified into the air ready for an ignition source. But just to be on the safe side, if you do go forward with putting Propane in the system, I wouldn't let someone light up right after getting in. Hopefully though if the gas was strong enough to explode, it'd be more than strong enough to smell the pungent stuff they put into it.

[blurooster]

this couldn't be any worse than making hydrogen gas in a glass container under the hood, go figure

[cgrey8]

I almost bought one of those just to tinker with. But then my engineering mind kicked in. If those things could really make you massively more MPG, it is breaking the laws of physics. After all, it takes energy to spin the alternator to make the electricity used to break water into hydrogen-n-oxygen. Law of conservation of energy says you won't get back out of something what you put in. So if you put X amount of energy into the alternator that is then used to make hydrogen to burn in your engine, you won't get anywhere near X amount of energy usage back from the engine. From that standpoint, hydration is a negative-sum addition.

The best you can hope for is the presence of hydrogen improves the efficiency of the combustion by more than the "drag" the alternator is putting on the engine. If that occurs, then you will realize a small MPG improvement...but it'll only be a small improvement at best.

[v8ranger]

But gas doesnt flow through the inside of the car either, the a/c does. One minute your having a cig on your way home, the next your a/c spings a leak and POOF!!!! lol......

[plowboy34]

Propane has been used in A/C for years. As cgrey said propane is heavy so if a leak is there it just keeps building up, it will not dissipate. Then it can go off like a bomb, gasoline will not go off like a bomb unless in vapor form. As a liquid in your tank it is relatively harmless. Also if you develop a small leak inside the cab area of a vehicle you may not know it and you could fall asleep at the wheel and/or passengers have long term affects. Will it get cold in your A/C system, yes it will. Do I consider it safe, absolutely not. Way to many things can happen in my opinion. Small leak and someone fires a cigarette up....BOOM....you were cool but you are dead. Seriously warpig, think about it. Your family is at risk. Just a crazy farmers opinion.

[v8ranger]

I can remember when chevy use to have the gas tanks behind the seat inside the cab. That was back in the 60's and I think early 70's.

How much cooler can propane be than 134? I know my a/c blows at about 45 to 50 degrees. Thats plenty cold enough. But maybe if you lived in Arizona where its 120. But still risky in my opinion.... I would rather be alive and hot than dead cold.... but thats just me.... A/C systems are more prone to leaks than any other system in the car. But again, thats just my opinion....