A/C using Non-CFCs

[Jinx]

Does anyone know what it takes to convert a conventional A/C system to a non-CFC system? I understand the compression ratio must increase to get the same amount of cooling from the non-CFC refrigerants.

Also, what are some names of non-CFC refrigerants? (Has anyone heard of SUVA?)

Thanks,

• Jinx

[kanicbird]

Ammonia is one of the most efficent refrigerants but could cause serious trouble if it leaks - it is used in industral applications. Also propane had been tried as a direct replacement for R-12 with limited success.

Basically any phase change can be used for refrigeration under some conditions (though it may not be practical).

Also compressed air is sometimes used for airconditioning. The air is compressed which heats it up. THe compressed air is allowed to cool under pressure and then expanded where it cools further. But since there is no phase change it isn’t the best method. I think some jets take some of the air entering the engine after compression to provide a/c for the cabin.

[Rick]

there are several things that have to be done to convert a car from R-12 to something else.
first any remaining R-12 must be recovered using proper equipment (venting into the air doesn’t qualify)
Next you have to decide what to fill the system with. While there are several alternatives on the market R-134 is the overwhelming choice. This is becasue the government has a regulation that all of these gasses have to be recovered and not vented. A seperate machine is required for each different gas. Shops are set up to recover R-134 because that is what the OE’s are putting in new cars since 1993. Before you hit reply, how does the shop know what is in your A/C system? They use a sniffer to check the chemical content of the gas in your system and if they don’t have the equipment they will probably refuse to service your car. (This assumes a quality shop, if you take your car to Freddies Fly by night you pay your money and takes your chance)
One other side note, Propane is flamable. I’ll be dammed if I want anything like that pressurized in the passenger compartment of my car.

OK having decided what gas to fill the sytem up with, the system must be broken into and a different oil added. The mineral oil used with R-12 doesn’t mix with R-134. Ester oil is added which causes the two to mix. The receiver/drier or accumlator will be changed to one that is compatable with R-134. A different expansion valve or orfice tube will/may be required. Lastly the fill fittings must be changed so that no idiot can come along and put R-12 back into the system. Lables must also be attached to alert people to the fact that the change over has been done.

After all that, suck the system down to a deep vacuum for the recomonded time and recharge with the correct amount of R-134.

Enjoy the cool.

Many car makers sell conversion kits to change the car over that have all the parts necessary to do the conversion. In addition I am guessing that a good parts house will have listing for what is necessary to do the job.
I do not consider this to be a DIY job. Not that the work is that complex, their is a lot of specialzed equipment required.

[Tedster]

I can say that propane works great – very cold A/C in a dodge charger a buddy of mine had. I would be leery of it, though. Don’t try it at home.

[kanicbird]

Isn’t r-134a a CFC?

The problem w/ propane is it’s smaller then freon and more able to leak out. And the fear of it exploding your car into a big fireball. Has there ever been an incident of that happening from a R-12 to propane conversion? Also I don’t think they use straight propane - it’s mixed with something else IIRC - maybe R-12.

[Rick]

Ok I didn’t say that Propane wouldn’t work, I said that I consider it dangerous and likely to put you in a situation where no one wants to service your car because they do not have a recovery machine for the blend in your car.
I did a little looking and most of the blends that I found that contained propane, or butane or isobutane were mixed with R-134 (!) or R-124 or R-22. If you are going to go with a mix containing R-134 then why not just put in R-134 and have something that can be serviced legally?

Here is some info from the EPA about retrofitting

What steps does EPA require when retrofitting air- conditioning systems to use alternative refrigerants?
A. During retrofitting, technicians must:

attach a unique fitting and label;
remove the CFC refrigerant before filling the systems with an alternative;
use recycling or recovery equipment during refrigerant removal.

This is what I covered in my post.
Further

Q. Has EPA declared any alternative to CFC-12 for use in vehicles to be unacceptable?

A. Yes. The Agency has determined that OZ-12 and HC-12a are unacceptable for use in motor vehicle air-conditioners because of unanswered flammability concerns. It is illegal to use them as a refrigerant in vehicles.

And

Consumers need to beware of false claims about alternative refrigerants. They should purchase only alternatives that have been listed as acceptable by EPA based on health and safety considerations. At present, R-134a is the only alternative refrigerant that has been fully tested and recommended by vehicle manufacturers. (R-134a contains no chlorine and therefore does not harm the ozone layer.)

From this page
we have this statement

Misleading Use of “Drop-in” to Describe Refrigerants
Many companies use the term “drop-in” to mean that a substitute refrigerant will perform identically to CFC-12, that no modifications need to be made to the system, and that the alternative can be used alone or mixed with CFC-12. However, EPA believes the term confuses and obscures several important regulatory and technical points. First, charging one refrigerant into a system before extracting the old refrigerant is a violation of the SNAP use conditions and is, therefore, illegal. Second, certain components may be required by law, such as hoses and compressor shutoff switches. If these components are not present, they must be installed. See the section below on use conditions for more information on these points. Third, it is impossible to test a refrigerant in the thousands of air conditioning systems in existence to demonstrate identical performance. In addition, system performance is strongly affected by outside temperature, humidity, driving conditions, etc., and it is impossible to ensure equal performance under all of these conditions. Finally, it is very difficult to demonstrate that system components will last as long as they would have if CFC-12 were used. For all of these reasons, EPA does not use the term “drop-in” to describe any alternative refrigerant.

Bottom line R-134 is the only gas that you can have installed in your car that guarrentees compliance with the rules, serviceability and and recomondation of the car maker.