lazy394

Im lost now with the A/C gases. A recent engine fire meant the engine bay had to be re done along with it a replacement compressor.
I am told if I run a Hydrocarbon refrigerant there is no warrantee. I was under the impression 134a ran at twice the original pressure of the Freon system and is as bad for the environment , if not worse.
Is there anyone knowledgeable on this and can offer some advice.

MDchanic

First, hydrocarbon refrigerants, such as propane, are flammable, and I can see why they wouldn't want to warrantee them, as well as why, considering recent events, you might not want to use them.

R134 runs at a higher pressure, but not twice as high. The difference should not be a problem for a normal A6 compressor, which I believe is the one you have.

The main problems with R134 are that you have to recalibrate your POA valve for it (not too difficult, Rob has posted on this before) and that you have to use a different condenser format to properly get the heat out of it. Also, you need to use a different receiver/dryer desiccant and you should use modern hoses, as the oil used by the R134 can soften the older rubber formulation over time.

We all have different preferences, but just using R12 is probably the simplest and most effective solution.

As far as being "bad for the environment," if you feel so personally all-powerful that your use of whatever refrigerant in one old car is going to end the world as we know it, then go ahead and use that as a criterion.

- Eric

lazy394

Eric,
Thank you for your help. Your on the money with my ,and my insurers, concern over the flammability of Hydrocarbon based gases as 90% of the damage done was caused by the burning gas being released from the A6's relief valve.
Subsequently all the hoses have been changed to take the hot gas bypass system out ( electronic thermostat is now installed) and receiver drier are renewed from a local model Holden that only ran 134a, and the Thermal expansion valve is just over a year old. This makes a transition to 134a easier.
R12 is not available as an option having been outlawed years earlier.
You mentioned modifications to the condenser, what needs to be changed and why?

Thanks Scott

MDchanic

You need a "crossflow" or "parallel flow" condenser, instead of the "serpentine" condenser your car came with.

Crossflow condensers are made like your car's radiator, where the fluid enters the tank on one side, and can flow through any or all of the tubes of the core to get to the tank on the other side, and then out.
Serpentine condensers have one or two tubes that snake through the cooling fins back and forth from start to finish.
Crossflow condensers flow more refrigerant with less restriction (read: "less pressure").

You may or may not be able to get an exact replacement crossflow condenser for your year and model, the way you can for a '68-'72 A-body, but you can definitely get a universal one that will fit.

As for R12 - Are you certain that it is really illegal?
Here it is legal if installed by a licensed installer (and it's easy to get the license yourself), but manufacture of it is either illegal or very limited, making supplies somewhat scarce (I can still find 12oz cans for $3 a can on occasion, though). It may be that people around you think it's illegal, when really it's not.

- Eric

lazy394

Looks like another challenge lol.
Thank you for your help, really appreciate it.
I may very well be a victim of the 'Illegal" hype too, I will look into it a bit closer

Mike77

Not illegal??? and a "licensed" installer ?? and "easy to get yourself"
I can absolutely guarantee you as a 30+ year Canadian red seal licensed refrigeration mechanical all of those statement are false.
I don't not know the American code, but it is not too much different than ours,. The Montreal Protcol of 1996 is applicable to all signing countries. You may want to check with your EPA before you start messing with refrigerants.


Mike

MDchanic

Mike,

At least you got the bold-faced part right.
And I am confident that I can say that I don't know the Canadian (or the Australian) code either.

As for the US, the US EPA says:

"Refrigerant Sales Restrictions

The sale of ozone-depleting refrigerant (such as R-11, R-12, and R-22) in any size container has been restricted to technicians certified either under the program described in Technician Certification above or under EPA's motor vehicle air conditioning regulations. The sales restriction covers ozone-depleting refrigerant contained in bulk containers, such as cans, cylinders, or drums.

The restriction excludes refrigerant contained in refrigerators or air conditioners with fully assembled refrigerant circuits (such as household refrigerators, window air conditioners, and packaged air conditioners), and HFC refrigerants (such as R-134a and R-410A).

Under Section 609 of the Clean Air Act, sales of CFC-12 in containers smaller than 20 pounds are restricted solely to technicians certified under EPA's motor vehicle air-conditioning regulations (i.e., Section 609 certified technicians). Technicians certified under EPA's stationary refrigeration and air-conditioning equipment (i.e., Section 608 certified technicians) may buy containers of CFC-12 larger than 20 pounds.

Section 609 technicians are only allowed to purchase refrigerants that are suitable for use in motor vehicle air-conditioners..."

So, Yes, R12 IS legal and it CAN be purchased legally by licensed technicians.

As for being easy to get, I guess you're calling me a liar.
I have a full, sealed 20 pound bottle of R12, and have purchased about a dozen 12oz cans over the past 2 years for $3 to $7 a can.
It was easy, and cheaper than buying cans of R134.

Incidentally, I am a "Section 609 certified technician" myself, having taken a brief test and paid $20 to a company called, if I recall, IMACA, about 20 years ago. That, too, was easy, and took all of about half an hour.

So what's your "guarantee" worth, Mr. "30+ year Canadian red seal licensed refrigeration mechanical"?

- Eric