A/C System

[Booyah45828]

Booyah what is your opinion on putting on a more modern design condenser when changing to 134?

The newer style condensers are definitely more efficient. That's why they went to them because of poor cooling from the old style when using r134a. R134a isn't as good of a refrigerant as r12 is, so if you can design the system to work more efficiently, it's always a good thing.

That's not to say an old condenser won't work with r134a. It's just You'll have lower cooling capacity in certain scenarios. Like when stationary at idle. But, I've added electric pusher fans to a system that had those issues and they were resolved.

 

[Booyah45828]

I'm also a newbie to A/C to. If you suck down the R12 system into an old propane take, will the R12 / air from the system settle in the propane take so you can vent off the air and leaving the R12 in the tank so you can reuse it ?. I have several old refrigerator compressors I could use to rig up a recovery system. When you use propane, is it 100% propane or a propane / R12 mix ? Also can you use a compressed air line oilier to inject oil into the vacuum side of the vacuum pump filled with mineral oil to keep the pump lubed ?

R12 and air won't separate out like oil and water in a propane tank. Separating refrigerant from air is something that is almost impossible for a person to do without specialized equipment.

If you're recovering refrigerant from old appliances, you should evacuate all air from the lines and tank before puncturing and recovering from the appliance system. That will keep your air ingestion to a minimum.

R290 is refrigerant grade propane, meaning it's pure propane gas. BBQ gas isn't as pure as r290. You'll have to look up specific refrigerants to see what their composition is. I'm unaware of any refrigerants that are an r12-propane mix.

A compressed air line oiler won't work to inject oil. It's very likely that the o-rings and other pieces inside of it aren't rated for refrigerant use. I wouldn't worry too much about oiling the suction side of a vacuum pump. In my experience, most pumps have their own lubricant and lubrication system, so more lube isn't needed.

 

[chris142]

The newer style condensers are definitely more efficient. That's why they went to them because of poor cooling from the old style when using r134a. R134a isn't as good of a refrigerant as r12 is, so if you can design the system to work more efficiently, it's always a good thing.

That's not to say an old condenser won't work with r134a. It's just You'll have lower cooling capacity in certain scenarios. Like when stationary at idle. But, I've added electric pusher fans to a system that had those issues and they were resolved.

That is a common misconception. R134a Is MORE efficient than R12 was at removing heat. R134a can overload an R12 condenser and cause poor cooling and high head pressures. The r134A condensers are designed to handle the increased load from R134a.

 

[Booyah45828]

That is a common misconception. R134a Is MORE efficient than R12 was at removing heat. R134a can overload an R12 condenser and cause poor cooling and high head pressures. The r134A condensers are designed to handle the increased load from R134a.

Turns out you're right, I guess I was under the impression that since the pressures were higher, the heat carrying efficiency was less.

 

[RuzzL]

r134a is also being phased out and has never been an efficient refrigerant. I'm going the new flammable route on my build. https://www.es-refrigerants.com
Also, the laws have changed in the last several years regarding r12/134a replacement.

 

[Booyah45828]

I saw that envirosafe stuff linked earlier, and wondered what it actually was. So, in case anyone else was wondering, the envirosafe r134a substitute is 72.48%propane, 26.52%butane, and 1%dipentene.

 

[IDIBRONCO]

the envirosafe r134a substitute is 72.48%propane, 26.52%butane, and 1%dipentene.

Sounds like it may be slightly flammable to me.

 

[IDIBRONCO]

The flammable stuff sounds like it may work better than the regular freon anyway.

 

[chris142]

Turns out you're right, I guess I was under the impression that since the pressures were higher, the heat carrying efficiency was less.

I specialize in auto AC.

 

[Booyah45828]

Sounds like it may be slightly flammable to me.

Just slightly , no more worse then the 40 gallons of fuel most vehicles have on board.

My biggest issue is if the evaporator inside leaks, you could have a cab full of propane. Hit the unlock switch on your keyless entry and watch the windows blow out.

 

[Booyah45828]

I specialize in auto AC.

I wish I could do that. Doing ac work is one of the few things I enjoy about my job, but around here I'd only be busy for a few months at a time. Hard to make a living that way.

 

[franklin2]

Just slightly , no more worse then the 40 gallons of fuel most vehicles have on board.

My biggest issue is if the evaporator inside leaks, you could have a cab full of propane. Hit the unlock switch on your keyless entry and watch the windows blow out.

I am guessing they do not put the "stink" in the propane for A/C systems like they do for normal use propane?

 

[Booyah45828]

I am guessing they do not put the "stink" in the propane for A/C systems like they do for normal use propane?

I'd say you're correct. Propane fuels usually will have the smelly stuff added so you can find leaks. I don't know if r290 would have that though.