C3 (1974) A6 A/C Compressor Conversion

[Paul L.]

Can a 1974 A6 compressor (and whole A/C system) be converted to R-134? I don't believe I can get R-12 in Canada. If so, any idea of typical costs of this conversion?

[Larry M.]

Re: C3 (1974) A6 A/C Compressor Conversion

Paul:

The short answer is YES it can be converted to 134a. Regarding cost, I would recommend that you find a Canadian AC shop that does this type of work and get an estimate. Get a couple competitive estimates if you can.

To perform this conversion legally and correctly, the compressor should be removed and the old mineral oil drained, the entire system should be flushed and dried to remove remaining mineral oil, the o-rings should be changed, the receiver/drier replaced with a new one containing the proper dessicant, new refrigerant oil charged into the system, and the high and low pressure fittings changed from the old type to the 134a type.

I am not certain if 1974 used a POA valve, something similar, or had changed to a low pressure cycling switch on the compressor suction. (I know 1972 GM cars still used a POA and 1978 GM cars used a low pressure switch) Either way, the POA valve should be reset or the low pressure cycling switch changed to one that is better suited for the 134a pressure difference from R-12.

Then pull and hold a good vacuum, charge the 134a refrigerant, and road test the system.

My guess for the cost for all this, done in a professional AC shop, will probably be around $500. Others may have a better cost estimate.

Larry

[Dick W.]

Re: C3 (1974) A6 A/C Compressor Conversion

By '74 GM had gone to the VIR (valve in receiver) system. I see no reason that it could not be converted, although it can sometimes be hard to replace the desiccant due to the location. If you do attempt this yourself, lubricate the fittings well with a good penetrating oil and let them soak. It is very easy to damage the lines if a fitting seizes. Be sure to use wrenches on both sides of the fitting. If the desiccant bag has ruptured you will need to remove the condensor and thoroughly blow it out with compressed air. The bottom of the condensor is the lowest point in the system and will gather quite a bit of debris. Any fitting that you disturb should have the "o" ring replaced with one that is compatable with the new refrigerant. Once the system is drained of most of the old oil and reassembled, evacuate it for at least 3-4 hours to remove the moisture. Also take note that a conversion to R-134a does not require as much referigerant as one with R-12. Close attention to the charge is necessary. Overcharging or undercharging by a small amount will make quite a difference in temperature. I have converted several C-3's and have had a couple of them to get well under 40 degrees.

Good luck

[Paul L.]

Re: C3 (1974) A6 A/C Compressor Conversion

Thanks Larry and Dick. I'm way beyond my depth when it comes to A/C so a couple of estimates from professional shops that remember an A6 compressor seems in order. The first step will be to determine why the R-12 leaked out in the first place. I will probably (in April-May, after winter) get a diagnostic test done (with estimate) and see if the cost of repair and conversion is worth the 3-4 times I would use A/C here in the summer. The car is a roadster and in a certain way, A/C does not really make sense in our climate when the top can be simply dropped. We rarely see 86*F (30*C). The car is coming north from the USA in coming weeks and I am sure more pressing issues will need monetary attention. But I DO like all systems to work.

[Dick W.]

Re: C3 (1974) A6 A/C Compressor Conversion

One point that I forgot to make earlier. It is recommended that unless you have a major component, such as compressor, evaporator, etc, failure that you recharge system with R-12.

[Paul L.]

Re: C3 (1974) A6 A/C Compressor Conversion

Dick,
The local GM dealer will not even talk about R-12. It is verboten here.

[Terry M.]

Re: C3 (1974) A6 A/C Compressor Conversion

Check with your chapter mates -- there may be a shop or individual who does R12 work "on the side." Of course going this route, if it is available, may entail some risk -- which can be minimized by word-of-mouth recommendation by satisfied customers.

One needs to be assured that whoever you chose to work on your car has experience with VIR (Valve in Receiver) systems. Anyone with this experience is not likely to be youthful.

One of the joys of the VIR system is that the desiccant can be easily changed in the receiver, but I am not sure desiccant that is compatible with R134 is available for these systems. They were used only briefly, and there is not much market for service parts for them any longer.

[Dick W.]

Re: C3 (1974) A6 A/C Compressor Conversion

I just check and Four Seasons has a R-134a compatable dessicant bag for the VIR systems

[Michael G.]

Re: C3 (1974) A6 A/C Compressor Conversion

I am also trying to get the AC up and running. I thouhgt I would see about the accessabilty of R-12. Just received a response from local distributor. No small can available. Large bottle cost $1,000.oo +. I honestly don't know what the going price is now. Is this where it has gone, or is this guy trying to get rich off my situation?
Mike

[Michael W.]

Re: C3 (1974) A6 A/C Compressor Conversion

Paul,

As advised on one of the other boards, repair of R12 systems is NOT illegal in Canada- only the sale of refrigerant to unlicensed persons is.

I stopped by my local garage where I have my daily drivers maintained, he has all the tooling and equipment required to legally work on R12 systems.

I'm sure you have something similar in your area.

[Paul L.]

Re: C3 (1974) A6 A/C Compressor Conversion

OK, Michael, I can 'phone around/try but I am not hopeful. The 1994 Montreal Environmental Accord basically put the end to R-12 in Canada. It can be recycled but no longer produced.

[Jim T.]

Re: C3 (1974) A6 A/C Compressor Conversion

What a repair shop will tell you on the phone and what one will tell you in person, could be different. I do not believe R-12 is still produced/manufactured in the United States any longer.

[Joe L.]

Re: C3 (1974) A6 A/C Compressor Conversion

R-12 is no longer manufactured anywhere in North America and may or may not be manufactured elsewhere in the world. In any event, manufactured or not, it's still available. The primary deterrent to its use is cost.

Something else to consider: R-134a may be on its way out, too, in the not-so-distant future.

[Dick W.]

Re: C3 (1974) A6 A/C Compressor Conversion

R-134a is on it's way out, but one of the replacement's that they are talking about will not work in the old R-12 systems. That is CO2. Pressures on the high side could get as high as 1,800 psi. And it is slightly flammable. The second mentioned alternative is R-152. It is almost a drop in replacement. I think that the Europeans will drive the next generation of refrigerants. There are some add on systems being manufactured in the US that are using R-152. Y'all reclaim and recycle all that R-12

[D S.]

Re: C3 (1974) A6 A/C Compressor Conversion

I have over 24 cans of R-12 in cool storage and can get it by the dozen on a telephone call here. No license or certification required. It runs me between $10-$15 a can. All three of my vehicles require it. '66, '70, and '93 Chevrolets.