Do you have to change the lines, or just the compressor and accumulator? Also, I think there's a line filter somewhere. My compressor is starting to go, so I'm thinking I might just go with the 134 for cost effectiveness. I know it isn't as hot as a gas as R-12, but for anybody using it, how well does it cool. Somebody told me that you only use like 85% as much of the 134 as you would the 12, and that then the cooling abilities are almost identical. Any comments? Anything I'm not thinking of?

nope, all that's changed is the fittings, and in my case all those leaky seals.

From my experience, 134A is not as cool as R12. My dad has 24 trucks and all of the new ones have 134A while he has an old one still having R12. The one with R12 can fog up the windows while the 134A results in having to keep the air alomst on high the etire time. Therefore, we do not think it cools as well.

Tim

Ringmaster is absolutely correct. The latent heat capacity of R-134a SUCKS compared to R-12.

If you don't mind changing to barrier hoses (probably a good idea anyway with 10+ year old hoses), you can use R-414B. It actually cools slightly better than R-12 and at lower presures for less strain on your system components. It works great for me and keeps the cavernous interior cool even with glass 'T' tops.

I wouldn't bother with R-134a in a system that doesn't have the larger coils designed to work effectively with it.

Just my 2¢

Vader! Please more info on the R-414B!!!

I put 134A in my R-12 system and it sucks. My compressor is going out tho (OEM 122K miles on it) so if I'm gonna blow all sorts of money on an A/C system I want it to work well....the minimum strain thing is also enticing.

TIA!

top

R-414B is a alternative refrigerant, marketed under the name Hot Shot.
It is a blend, and requires a slightly different installation. Namely introducing the refrigerant as a liquid into the cars system.

Must be installed properly or the dreaded seperation could occur !
Also requires a 609 to purchase in can form.

Properties:
Boiling Point...-29.8°F.
Critical Temperature...266.8°F.
Heat of Vaporization...92.8 BTUH/lb
Enthalpy liq @ 20°C...28.72 btu/lb
Vol-liq @ 20°C...0.0131 lb/cf
Den-liq @ 20°C...76.27 lb/cf

Components:
*R-22.....50% (wt)
Chlorodifluoromethane
*R-124.....39% (wt)
Chlorotetrafluoroethane
*R-600a.....1.5% (wt)
Isobutane
*R-142b.....9.5% (wt)
1-Chloro-1,
1-Difluoroethane

You might call your local automotive AC service folks, and see if they support R-141B (Hot Shot). If not there are other alternative blends that work good as well.

Ron

Gm's position on conversions originally was NOT to change R-12 systems to R-134a, however in a more recent service bulletin they now say if done correctly it is the preferred method of service. I just helped to convert an older Monte-C over and in these last few days in the Pennsy area I was surprised how well it worked. The owner replaced lines and seals with OE ordered from GMSPO. Thier replacements ARE 134 compatible. We also replaced the accumulator. As Vader points out, the system components for 134 systems are a little more robust but decent performance from the AC can be achieved if done correctly. I believe he used a different orifice tube also. The boiling point of R-12 is -21.7 deg.F, R134 is -15.07 deg.F so you see there is a major difference. It generally equates to a 12-20% reduction in cooling efficiency when used with R-12 parts. I have been sitting on the fence with this one, I am on the original charge on my 89 and it is losing steam. I was not familiar with the one Vader points out, gonna look into it though.

has anyone heard of freeze 12? how about this blend. is it any good? i heard it works just as good as r-12 and alot better than r-134. ppl say it requires no changing of oils or lines to work with it.

Freeze-12? R414-B. Niether requires and oil or seal change, but changing the hoses to barrier type is recommended. And if you have universal certification, you can get it in big cylinders.

What in the world is a barrier hose?

Thanks for all the other responses...

make sure to pull a good vacuum on the system before any retrofit.

also, this article may be of intrest:

http://www.iroczone.com/projac01.html

Vader and other members should look at this page. it's looks like Freeze12 sucks balls. HotShot is not the greatest after all. i will try R-406A though and see how that goes. it looks promising....

http://www.autofrost.com/oil/

refrigerant blends are likely to cause you problems down the road. would probably be a wise idea to choose either r-12 or r-134a.

r-12 was around $30 per 12oz can last i checked, r-134a can be acquired for around $5 per 12oz can.

When I bought my car A/C didn't work at all. I spent the money and bought one of the good 134a retrofit kits ( not the all in one can crap ). I took everything out and flushed all of the old oil and crud out of the system. Then I put it back together and added the new fittings. My 134a system can fog the windows, and keep me cool with the top down. I heard those retrofits that don't open the system will ruin everything.

What's the name of the kit? My system is far from good so I want to do the conversion right the first time.

Sorry I don't remember I got it at O'reilly's though, it was like $45.

I live in Florida and there is a lot of AC shops down here and NONE recommend the use of blends. I need to have my AC charged and I was looking for something better than 134a but not as expensive as R12. After researching the boards and the net, MP39 / R-414 seem to be the answer, but I could not purchase it without a license so I started to look for a shop that used any of the these blends and I could not find a one that used it. My choice was 134a or R12 or nothing. I guess I am going to have them put in R12 because I need cold air. The going rate was $48 a lb bend over!
All of this started me thinking (look out) could a person modify the box where the evaporator goes, and install a bigger evaporator out of a modern 134a system? How would an evaporator + expansion valve setup out of a 4th gen work, (or any other car for that matter)?? Newer 134a systems work great and if we could modify ours to work with that same performance that would be great , better cooling and cheaper to maintain. I know there are a lot of smart people that use this site and someone here could do this or at least knows tha answer.

If your car will go more than a season or two without topping the charge. I'd stay with r12. I just changed my GTA over to 134, Had very little pressure in it when I bought it two years ago. I did pull a very good vaccum on it before I charged it up, and it does work good. It'll blow 38 degree air out the vents after the cool down. I can't complane on that.

converting R12 to 134a, you will only notice maybe 2 degrees of difference, or a little longer in cooling the car(maybe 15 seconds)the 134 has smaller molecules than the R12. If you do the conversion correctly, you are supposed to change the o rings, the dryer(which should be changed every 30 or 40 thousand miles anyways but no one does it)the orfice tube, completely drain the system, do a vacumm test on it, use the correct estercool oil, or PAG oil if you want, then charge the new system with 80% of the R12. We have done this conversion probably almost 75 times in the last season. Cheap blends are not recomended by estercool or any other reputal cooling company. Bad blends use propane, and lots of other bad stuff in there cheap mixes, if you mix the wrong stuff with the wrong stuff, BAMMMM you have a big bang. I am going off of what the experts teach us at work. If you do the conversion probably, flush the system, vacuum test it, you will not have any problems, and the cooling is almost identical to the R12. The 134a i think is 7-9 dollars a pound, and the R12 is almost 50-60(i can check at work monday if you want)our general rule of thumb is, if you are going to keep the car more than 2 years, its worth converting, especially if you have a leak. by the time you fix the leak, fill the system with r12, you will have almost reached the cost of converting, and then the 134 is way cheaper. but beware, after a few years, they will start jacking up the price of 134 because everyone is using it. there is enough R12 out there to last for atleast 7 years, dont let anyone tell you, some companys are making R12 copies and are selling it. the stuff they use in it, is questionable at best. sorry this was long, i am half drunk, so that has something to do with it. thanks . lil jay

I have the R134 retrofit. it SUCKS in city driving or with the car idling, it blows out maybe 70-80*, with about 105* outside here in texas.. and so city driving its not worth it to use A\C, too much stopping, but on the highway its a whole different story. 1 hour trip out to the drag strip last summer, with a thermometer in the car, got the temp in the passenger compartment down to about 50*

i would suggest not necessarliy a new evap. but a larger condensor

Well, I will say this. I converted my 83 Trans Am to R134A and it blows just as cold as R12. Similar results with my 68 Charger. Works good for me.

The evaporator is fine, and also the orfice tube. The issue is the condenser. Systems converted to 134-A have poor city driving and idling performance. But on the highway, they work very well. A larger condenser would be the answer, but I have yet to be able to find one. Another option would be a "pusher-type" electric cooling fan in the front of the radiator wired into the fan control switch in the A/C system. If anyone has tried this, how did it work?

This may sound like a dumb question at this point, but my knowledge about air conditioning is somewhat limited. What/where is the evaporator?

The evaporator is the small heat exchanger located in the ventilation system near the heater core. It is on the low pressure side of the A/C system, directly after the orfice tube and before the accumulator. It is what cools the incoming air to the cabin of the car. The condenser is the larger heat exchanger mounted in front of the radiator that removes the excess heat from the refigerant and is on the high pressure side of the system, after the compressor. The names of the components describe exactly what they do. The evaporator evaporates the liquid refrigerant into a gas at constant pressure buy adding heat, and the condender condenses the gas into liquid at constant pressure by removing heat.

if your 134s conversion doesn't work, it wasnt retrofited correctly. or quality 134a refrigerant wasnt used. IMO. I have done to many of them personally and so has my boss in the shop with no combacks or complaints. If you do the swap right, you wont notice any difference. Hot Shot, and some of the other blends out there are junk IMO. Its like anything else, you get what you pay for.

Well, i'll throw in my personal experience. My A/C has been in-op for years so last week I replaced the Compressor, Dryer, and Orifice tube. I switched to R-134 (it was free, so was the PAG oil, much better than paying for R-12).

I threw a thermometer in a vent and the R-134 was only able to achieve a low of 48 degrees farenheit. I cools fine but it never gets to the point where you say "damn it's cold". It achieved 48 degrees within 1 minute but that's as cold as it gets. It's good enough for me but maybe not good enough for others. Just my 2 cents.

There's nothing wrong with 48. In order to get colder than that, you have to run the evaparator real close to freezing. Which I do, but I don't do any long drives. You can also run them too cold, they'll freeze up if run for a long time.

To address the above problem-I adjusted my low press switch about 1/4 turn counter-clockwise so that the compressor will con't to run at idle and slow speeds-helps a lot! Also if you overfill with 134 it'll not blow near as cold-only fill with 80% of what the system is rated for with r12. Also check out www.epa.gov/ozone/title6/609/retrguid.html It gives all the latest info on what works and doesn't.

My father has retrofitted 134 into R12 cars hundreds of times, and has yet to have somebody complain about it not cooling enough. Every time I've watched him do a conversion I've watched the digital temp gauge show 42* or colder. I've never seen a 134 retrofit blow more than 3* warmer than an R12 car. Obviously this might vary for others (I tend to trust Vader when he expresses an opinion) but I haven't seen it myself.

Usually the only people that I see bitching about 134 are the ones that did the retrofit themselves instead of having it done by a professional. DIYers tend to over or under fill the system, which will cause it to blow warmer, and in most cases, the reason that they do the swap to begin with is because the old stuff didn't work right. Well... if it didn't work with R12, why do they expect it to work with 134? If the R12 leaked out, the 134 will too. When it's done by a professional, they pull the system into a vacuum which gets all moisture out of the system. A professional will also make sure there aren't any leaks.

But anyway, off that soap box and on to another one. I think using 406, Freeze-12, R414-B and any of the other 400 varieties is a BAD idea. The stuff may work ok, but it's non compatable with 134a and not servicable by the vast, vast majority of the garages out there. It might work out ok for a DIY'er, but air conditioning problems are impossible to diagnose and fix for an amature, and when you need to have it worked on, nobody will touch it. Sometimes using the more conventional, somewhat less effective stuff isn't a bad idea. Everybody likes to be a pioneer and do their own thing, but when you're running a system that absolutely nobody can work on, you're just asking for problems.

if you want the system to function properly and parts to last you will need to have the system flushed, different oil installed and 134 fittings installed. r12 cools better in city traffic but at speeds the r134 does as well as the 12 as long as the system was converted properly. we used to convert alot of volvos where i worked. there are pressure differences between the 12 and 134 compressors but the 12 will get you by

I have been trying to figure out what to do with my 89. My AC is still cold but is starting to struggle with very hot days. Yesterday I had the opportunity to speak with a regional tech rep for one of the big three(not GM)who is a close friend of my dad's. He told me this- He does not recommend converting R-12 systems to 134 for several reasons. First reason is that the 134 is not as efficient as 12 (we all know that). Second is that he has seen many converted systems and that many seem to develop problems within a couple of years after conversion. Third is that 134 attacks even the seals that were designed for it. In my case he told me to recharge with 12(my system is tight)as long as it is available. In his opinion 12 systems will run almost indefinitely with few problems as opposed to the numerous problems and complaints with 134 systems he sees on a daily basis. Anybody use this 12a stuff? Like some input about it.