Volvo RWD 700 Forum

Assuming I can find a way to hook up a can of R134a... Would the actual refrigerant interact with the R12 or old oil? I think my system is just low on refrigerant. It works, but not well. If I can find the parts, I'd be glad to retrofit it to R134a, but I think the tube from volvo is like $200.

Anyone know for sure, besides warnings like "don't play with AC you'll blow yourself up?"

-Will
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1990 740 Turbo, on its way to stock specs, maybe beyond

The A/C was out on my brother's '89 Oldsmobile and we just put some R134 into it. A/C works great now, and it was a cheap fix thats lasted for a year now. Your mileage may vary though.

OK, I read that loud and clear.
I found something called Autofreeze, AKA R-406a I think. Seems like it's pretty good from a bunch of forums I've read through.
I think it's just a low pressure situation - I have the following symptoms:
compressor cycles on and I assume off(I'll check), so does aux fan when hot.
When I change the engine rpm drastically (downshift and back up) the temp at the vents drops drastically. The AC Dryer (big silver can) is no longer frosting up, and is actually not much cooler than 80F. It's a lot cooler than the engine bay though. (I think it still frosted up last year, but I know it did the year before that.)

It's been 110 the last couple days, but the vent temps are only about 60F after running the engine hard for a while.

Does the engine have a high-rpm compressor cutoff? I think I'm either low on refrigerant or have some kind of compressor stays on too long situation.

Thanks for all the responses. I see now that R134a and Freeze-12 (which is 80% R-134a) are not miscible in the original mineral oil. (and freeze-12 sucks AFAIK).

And yes, I know of the partial pressure law - which says that teh total pressure is the sum of each pressure of each gas added up. so if I only have 25% of my original gas, I have only 25% of the pressure. Adding volume equal to 75% of the original gas would give me the 100% pressure the system should have.

Thanks everyone,
Will
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1990 740 Turbo, on its way to stock specs, maybe beyond

In a flat answer NO!

There is a law of physics called Dalton's Law.

"The total pressure of a confined mixture of gases is the sum of the partial pressures of each of the gases in the mixture".

Each gas behaves as if it occupies the space ALONE!

You have to remove all of the original gas.

There are other "drop in" refrigerants but they mean into a "empty system".

As far as oil you have to follow the manufacturer of the refrigerant recommendation.

Phil

Don't add R134a to an R12 system. They aren't compatible.

You can convert to R134a, add R12, or add an alternative refrigerant. An alternative refrigerant which works extremely well are hydrocarbon refrigerants. I use the Envirosafe product, http://autorefrigerants.com/co00033.htm. You don't have to do any conversions and it works well with the mineral oil used in R12 systems. It isn't legal to add to an R12 system, but I can tell you that it works excellant added on top of R12. Also check out Redtek, http://www.redtek.com/home.html.

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john

It will break the Carnot cycle? Not so sure it won't work, maybe not perfectly or for as long. Mainly, I just love mentioning the Carnot cycle. Its as sound as the hydrogen based fuel stretchers are phony. Thermodynamics is cool.

I have used a product called "Freeze12" for several years and it works great. The only problem I have it needs to recharged every year due to a slight leak. Do a search on the web and then call around to local shops to find it. I think you can mix it with R12 if you still have some in your system.
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1989 240, 1992 745

There are several DIY products available to recharge R12 and R134A systems. They use a hydrocarbon refrigerant that's more environmentally safe that the freon products above. However, if you ask any A/C shop, they'll tell you the substitute is snake oil or worse. You can't really blame them when they have thousands of dollars invested in R134A equipment. I've read many testimonials from people who resurrected their dead A/C with a hydrocarbon refrigerant kit when going the R134A conversion or recharge route at an A/C shop would have cost half of what their old car is worth. The kits are all over eBay and at various auto parts and Walmart stores for a bit more money.

It will not work. there is complete info in the FAQ; there are complete directions there. The short story, which I did a few weeks ago to my now expired 90 (see "Sadness" a few weeks ago), is to get the Volvo kit for around $80 or so, replace the accumulator (kit), change the orifice valve (kit, but maybe get the variable orifice valve separately), drain the compressor because the two different refrigerants use two different and incompatible oils and use the new ester oil (kit), vacuum the system thoroughly, and then charge it. Mine worked very well for the few days I had it, and many others report good results also.

Where did you get this kit? Is it the Volvo one? FCPgroton has it online for $175. It is pictured below.

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Paul NW Indiana '89 740 Turbo 140,000

Holy smokes, that's the one, I got it from them a couple of years ago for about $70-80, I don't recall exactly. RPR had it for $100 some time ago, I don't know current price there. $175, wow.
I only put it in recently which is why my results are recent but the price isn't.

The other refrigerants mentioned are very interesting, I had not heard of Envirosafe, that seems almost TGTBT; cheap, easy to put in, works well, dang. If I was doing it again I'd look into that.