134a

[Mancar1]

During all the under hood work on the 68 the past several months I somehow lost my R-12 charge
I have been looking for R-12 and it is getting $$$$ and harder to find. Thinking on converting to 134a or ? Any input from others who have actually done a A/C conversion, and if the cooling was acceptable, would be appreciated.
Thanks and keep on Trucking.....John

[sargentrs]

Not on a bump but I did it to my '90 Toyota Camry. Wasn't working before and needed a recharge so I converted to 134A to get it working again. Worked great as long as you were moving but got weak sitting still. But that might have just been the car, airflow thing, not the 134A conversion.

[thejunkman]

Most people I know that have done the conversion are not big fans of the 134a. I can tell you that r-12 is all over craigslist. Generally 25 bucks a can in my area. I guess things might be different in Cali.

[Mancar1]

Most people I know that have done the conversion are not big fans of the 134a. I can tell you that r-12 is all over craigslist. Generally 25 bucks a can in my area. I guess things might be different in Cali.

It is not the price as much as you have to be certified to buy it. I have a friend who is A/C certified, I am just looking over my options right now. Before ya know it summer will b here.

[1972hiboy]

Ive done the conversion on a couple different vehicles. One I remember was a 86' C2500 I had in high school. That setup froze my butt off. I was going through Manteca CA on a hot summer day towing the fishing boat to Pinecrest lake and I had to turn the ac down ( and I like being COLD) Think I thermometered it out at 34 degrees. Now my 93 dodge w350 I did the conversion on just wouldnt cut the mustard. I could never get the register temp to drop below 55 degrees, Its cool but just not really enough to sustain the cabin on a hot day. I think it comes down to the function/condition of the a/c system componets your working with. Ive heard that r12 gets cooler but 134a can freeze your finger solid on the spot upon direct contact. I wouldnt rule out a 134a conversion. Ive had good and bad results.

[fireguywtc]

My factory AC with factory style AC pump uses R134a and works good in the Texas heat. I did put in the biggest condenser I could fit on the front that is a more modern parallel style condenser. I have read that R134a needs more condenser area to dissipate heat since working at higher head pressures.

Overall with the cost of changing condenser and the work with flushing and changing out compressor oil, you will likely be money and time ahead if you can get some R-12.

[NM5K]

I remember I did my old Monte Carlo, and it was only so-so.. The main problem converting is the condenser
coil will be undersized for 134a. So you end up running a high head pressure unless you slightly undercharge.
Which generally means the system will not cool quite as well as with the original R12 running at normal pressures.
Since then, I've always recharged R12 systems with R12. It just works better.
But I suppose that is easy for me to say, as I have plenty of it.. I still have a 30lb drum of it that is almost full.
It's easy to get a EPA ticket. It's open book per say, and a no brainer.. You can get them online most likely, and
if not, can send for the test material. Once you have that, you can buy it. They have a special automotive
ticket that covers the 1 lb cans. I've got every EPA ticket myself.. Universal, plus the auto can ticket, plus an extra
410a certification, which actually isn't required, but I got it just fer grins..

[Randle]

I converted a 76 a couple the summer before last, put a rebuilt York compressor on and it did OK, it didn't seem like it was as cold when it set idling but going down the road you would have to cut it back.

[Mancar1]

Thanks for all the input
Keep on Trucking and stay when it gets hot.

[68RGR]

I got my EPA 609 certification by mail years ago. Allows you to service mobile air conditioners and to buy refrigerant.

See:

http://www.epa.gov/ozone/title6/609/tec ... certs.html

That site has a list of online testing sites. Seems the cost is right at $20 no matter where you go. The test is open book and isn't hard. (Well, it wasn't 20 years ago!) You can also order the test and take it at home but why bother? The site below charges $4.95 for each retest if you don't make the grade the first time.

http://www.epatest.com/609/openbook/

If you keep your eyes and ears open, sooner or later, you'll run across some R-12 at a reasonable cost. To me, "reasonable" is under $20 a pound . . . I saw some 12 ounce cans recently for $10 a can or $13.33 a pound. Local car dealer had 100+ cans listed on Craigslist last year for $15 for singles and about $10 if you took them all.

I can't help but think the price of R-12, as well as R-22 for fixed systems, will DECREASE as the demand declines. People are sitting on both types thinking they will cash in. But, as R-134a, R-410a and others are used more and more often, there will be less and less demand for R-12 and R-22. Plus, I am seeing more and more R-12 recovery equipment up for sale by garages and the like. That's a pretty good indication that there isn't enough demand for them to hold onto equipment to service R-12 systems.

Bottom line is, if you liked the way it worked when it was charged with R-12, the surest way to duplicate that performance is to stick with R-12.

[motzingg]

I'm no expert on AC systems, but i do have about a year and a half of Thermodynamics classes under my belt and i've done some research, as near as i can tell:

The r12 vs R134 unloading valve is calibrated differently. Thats what creates the backpressure which has to be higher for the higher boiling point 134 coolant to condense. There are also different seals (viton vs buna i think) in the compressor for 134 to work with the different oils. If you do the conversion and use the special backwards-compatable conversion oil, its very simple. The system wont be as efficient because the unloading valve wont be calibrated properly, but it seems to work pretty well. Probably has a lot to do with how your pump is geared and how tight your system is.

I did the retrofit last summer on a 'modern' 1991 escort and it worked great, but the 134 leaked down faster than the 12. Since i was putting a can in every spring, i figured it was cheaper to buy an $8 can (wal mart or sam's club seems like the best prices) rather than having to find the R12 at whatever price that was. Like folks have said, it doesn't work at low engine speeds because its not making enough pressure but at highway speeds it would get there eventually. Overcharging it a bit helped the situation, but it only ever got so good.

I've done some research into the hydrocarbon based refrigerants and they look promising, i think if i were to do another conversion I'd try something like that.

I'm piecing together a system for my truck right now and trying to decide between 134 or a HC based, i just worry about some of the HC brands compatability and sticking around for awhile. If they go out of business in 2 years and I need a recharge, how will i know what proprietary formulations are compatable with others.


A good buddy of mine rebuilt the system in his late 80's chevy using the 134 unloading valve and put new seals in his pump... i think it was a big old sanden type... it was crazy, uncomfortably cold, like even beyond modern luxury car standards, the only thing you could compare it to would be a freezer, and that was all with the r12 components, the only thing changed was the different unloading valve. You only need a big condenser when you are running at too low pressure and outside of the efficiency of the fluid.

If you want to 'do it right' and be done with it, i'd go that route, all new seals, new hoses, new quick disconnects (i understand those are a huge source of leaks) and replace the unloading valve with a 134 one. Put a new drier in the system, fresh oil, and pull down the vacuum. Fill it all up with 134 and forget there is even fluid in it because it will be off the maintenance list forever.

I'm not sure how hard those pumps are to rebuild, but i've worked in hydraulics/pneumatcs for years and compared to an engine, most of that stuff is dead nuts simple.