Stay w/ R12 or convert to R134
 

I have an 86 420 sel. The A/C has a low charge. There is a hose that is leaking from the drier to the condenser. There is still R12 in the system. Has anyone converted their AC to a R134? I read that it does not cool as well. Or should I stay with R12? The shop quoted about to $200 to evac and charge plus additional labor to change the hose and the drier and the cost of R12.

The other option is spend money on the DIY kit from ACkit http://www.ackits.com/merchant2/merchant.mvc?Screen=PROD&Store_Code=AMA&Product_Code=DIY-STARTER1 to do the conversion to r134 :( and learn to do this well. With this forum, I know I can tackle this job. Let me know what you guys think. I plan to keep the car as long as possible. Everything else in the car is working great.

Thanks,

John

I have converted 4 cars to 134 with no problems. I did this the cheap way, screw the fitting on the low pressure side and fill her up with one can oil and 134. Probably wouldn't hurt to have it evacuated but I have never done anything else. It's so cheap why not try it.

Dan

John,

IT really depends on your climate. If you live in the south and do stop and go traffic it will definately be noticably different. You can get an EPA license for R-12 for $15 on-line. R-12 gauges are cheap and the price per pound difference between R12 and R134a is not much this summer.

Do a search on Larrybible- there are some long threads on this subject over the years.


I would NOT convert my car.


Michael

Lots of opinions on this one.

Some say that an original R-12 system will not cool down well after conversion to R-134a.

Others say it will.

There's a member here named Stan Pittman. Look at his profile. 30 yrs. euro car experience. He claims that the 134a conversions do work. I went looking for this thread, but could not find it. In it, he told Larry Bible that he was full of !@#$. Webmaster probably locked down the thread. Stan operates out of South Carolina. I lived not far from there once and summers are hot & humid. If R-134a works there, it will work in many other HOT places.

I believe that a refrigerant conversion is a lot like automotive body work. There's a lot of prep involved and if you do not do it correctly, the job will end in failure whether you're replacing an R-12 system with R-12 or converting an R-12 system to R-134a.

Larry Bible has recently mentioned $14.00 a lb. R-12. He has also mentioned refrigerantsales.com, so I assume he's buying it there. I just looked on their WEB site and a single 30 lb. cyl goes for $575.00. That comes out to $19.16 a lb. - not $14.00. Even in bulk, it's no where near $14.00 a lb., so I guess he's getting it elsewhere.

I saw R-134a the other day for $7.88 - a far cry from $19.16 and a lot more accessible.

Do the job right and R-134a will work.

I purchased my son's 300e from a guy in South Florida who spent about $3200 on a complete new system with r134a. (evaporator, compressor, high pressure hose,blower, drier)

It blows about as cold and powerful as any car I have ever owned

The replacement parts are the reason why I bought the car....

I believe Larrybible's point is philosophical-

A W124 system holds 2.2 lbs maybe a touch more- say 2.5 lbs. At $20 a lb, that is only $50 for R-12. And if you got your R134a @7.88 (is that a lb or a can?)- anyway we're spliting hairs over $20-30?? Correct.

There is no doubt you can convert it to R134a for $3200 and have wonderful a/c. But why not just replace a leaky hose, a few small parts and have it up and running for $200-300?

I've been in R134 converted cars and most I find inadequate. For W124's they wire the aux fan to be on when ever the compressor is engaged to help.

Michael

Don't listen to anyone who lives in Canada saying r134a is great.
I live in Texas and can say without a doubt that R134a sucks.

Spend the extra 30 bucks and get some R12 from eBay.
It blows about 15 degrees cooler making it worth 10 times the money.

I've experienced that myself and upon inquiry learned that the owner did nothing more than buy a $20 conversion kit. That will definitely result in failure.

All of the succesful 134a converisons I experienced were properly done. Like I said above, do it right and it will work.

i just went through this. prev owner had converted to 134a. had a leaky hose, so new drier, evac, recharge with 134. 134 didn't cool that well, could only get it to around 50 degrees. in tampa, where it's hot and humid, it was most annoying, it took the car around 20min of driving to get the least bit comfortable. i took it back to r-12, now blows 40 deg.

if you can find a custom a/c shop (one that does rv's, collectible cars and the like) they can probably leak test the system, repair it, and refill it with r-12. i pd $70 per lb of r-12 at the a/c shop and i think it was worth it. the system only holds 2.2 lbs. $140.00 for r-12, vs $60.00 for 134, plus the flush. only worked out to about $50.00 difference. i also noticed that the pressures were about 75psi higher with 134. which equals more stress on the rest of the system which in my case has some 14 yr old parts in it.

you can get a receiver-drier on ebay for @ $20.00. you'll need that regardless of what refrigerant you go to.

also make sure your condensor and radiator are clean. i took the upper tie bar off and pushed the rad back and couldn't believe the gunk in between the condensor and radiator. i used some compressed air to blow it all out.

Do a search...

Leathermang and LarryBible are both A/C experts...they have both earned my respect and trust. I will believe what they say on A/C matters.

R134 conversions suck anywhere south of the Canadian border.

My W116 has the conversion...professionally done and it bites....I am converting it back to R12 when I am equiped to do the job.

And the "Drop in Replacements" aren't drop in and they suck even worse.

Do it right do it with R12....

In a humid environment, the transfer rate of heat out of the air is much higher. The humidity HELPS the a/c rather than hurts it. It would be much more impressive to have a system that kept a car cool at 90* in Denver on a dry day than Miami or Charleston, SC with their respective humidity levels at the same temperature.

I converted by 300SDL back to R-12; just was not happy with the cooling, especially after being parked outside. The previous owner had it converted to 134a only for the purpose of conversion in '98. The conversion was done correctly (complete flush, etc). I have the receipt and talked to the shop which performed the conversion.

Given my experience, I vote to stay with R-12 on a 126.

I had my mechanic convert the system in my 300E to r134a and I couldn't be happier. Since the conversion I have spent a year in Austin and two in Houston and the car cools as well as it did before the conversion (I would even say it cools as well as when we picked the car up in 94.) The reason I changed is there was a small refrigerant leak in the system that would necessitate a recharge at the start of summer. I decided it was easier just to recharge the system once a year and with r134, cheaper (Altough refrigerant prices have shot through the roof recently?????)

We have been converting to 134A since 1997 and have not had a complaint since. If you do it right you will have no problem. In my experience if done right it cools as good or better than R12.

In my 1992 BMW, i faced this same dillema.

The guys on the bmw forum recommended a product called freeze 12. Apparently its an ozone safe R12 replacement, that is approved by the epa. You can purchase it and install it yourself, no epa certificate required. You can also add to existing R12 without having to evacuate the system.

I've had great results with it in the BMW. All my MB's at this point are R134a from the factory so I dont know how well it works with the MB's.

You can find it on ebay for cheap, a full kit with like 3 cans and the gauge and can tap is like 38 bucks.

Hope this helps,

George

te"In a humid environment, the transfer rate of heat out of the air is much higher. The humidity HELPS the a/c rather than hurts it. It would be much more impressive to have a system that kept a car cool at 90* in Denver on a dry day than Miami or Charleston, SC with their respective humidity levels at the same temperature"

No!! We are talking heat load- there is much more energy that has to be removed through the evaporator with humidity than on a dry day. You must be thinking of the condensor being more effiecent! And yes, denver @ 6,000 ft has thinner air, so it does remove less heat.


Stan : Where are you located ? What do you consider a "proper conversion"??


Michael

Statistically, even a "proper" conversion will only last about two years before compressor problems. These statistics are based on well kept records involving over 200 conversions in the hot Florida climate.

Now that R12 prices have come down there is just no reason at all to convert.

Good luck,

I think the R4 compressors fail over time due to the extra R134a pressures. Maybe the A6 type compresssors in latter W124s hold up better to the R134A pressure.

Freeze 12 is not a R12 replacement...it is a blend , do a search on A/C blends....
everything sucks compaired to R12....

Anna Kornicova and Rosie O'Donnel are both women...and they both work as women...its the same thing right?

Yep, you can purchase and add it without certification. But you can't mix it with any other refrigerant (if you do, NO reputable a/c shop will EVER want to deal with you because it will contaminate their recovery system and they have to pay significantly to dispose of what's pulled out). You also have to switch the fittings to be correct for Freeze 12. It's just 80% HFC-134a and 20% HCFC-142b, not really much better than 134a in the first place. To do it properly still requires vacuuming the system out properly, replacing the drier and all o-rings, etc... It's a horrible alternative to a proper 134a conversion or staying with R12.

Looks like the stats you have are in conflict with what Stan Pittman reports. He does this for a living and since 1997(8 years) has had no come backs at his shop. His comment is on page 1 of 2.

As Stan said, it's all about doing it correctly. I would venture to say that many R-12 -> R-134a conversions are not "by the book" and I'd have to wonder if those "200 converions" were REALLY done "by the book".

We argue about oil, coolant and refrigerant. I'm out of this one.

What's next?....wiper blades?

For more than you ever wanted to know about car A/C go to EPA Test and read "Section 609". It goes over all the oil differences, the real (not word of mouth BS) differences between R-12 and R-134a and even the Freeze 12 snakeoils. The study guide is free, taking the test to buy your own R-12 legally (in the USA) is a mere $15.

I have a 1992 300E. The system was converted to R134a by the prior owner in 1997 when they had the evaporator replaced.

Last year I replaced the compressor, expansion valve and reciever/dryer and charged with R134a. The system works fine. I'm not sure but I recall the center vent temps would go down to about 40 degrees with ambient temps in the high 90 degrees. I live on the coast in South Carolina and it's very humid here. So far so good. I guess I'm lucky my system works great for now.

I have three other vehicles all with R134a originally and they all cool just fine, meaning vent temps from 40 degrees to about 45 degrees when the ambient is 90 to 100 degrees.

Again I say that the w124s have a different compressor than the early to mid w123s and w126s.

My 1993 w124 oe r134a, dual cooling fan gets the vent temps you describe however my two w126 R4 compressor R134a correct conversions would not get those vent temps at 90-100 ambient in my climate.

My co-workers one owner 1983 w126 300sd is oe R12 and has NEVER had anything done to the a/c system, it blows ice cubes.

Ask Stan Pittman the success rates for R4 compressor R134a conversions, and for how long, I am curious.

The statistics that I paraphrased came from a VERY TRUSTED source who posts often on mshop. I trust his records and experience over anyone else that I'm aware of. I will not comment on his findings. If he reads this thread and wishes to comment, then you will here the facts from someone with those facts to back it up.

I can assure you that his shop in Florida has done these conversions "correctly." He also is being very honest in admitting the problems that have been experienced.

If someone has done conversions for 8 years with ZERO comebacks, they deserve some sort of award for beating the law of averages. No matter how good ones work is, there has to be SOMETHING in 8 years. Either that or these conversions have only been done on very late model R12 equipped cars. As time approached 1993, the cars were more and more "convertible" as the makers started using different components in preparation for the changeover.

Most 91 or 92 cars regardless of maker will convert quite well.

After writing the above, I went and read Stan Pitmans post. He did not say that he has not had comebacks with broken compressors or the like. What he claimed was that his customers have not complained about inadequate cooling. What I refer to are broken components after conversion.

I still think that Stan deserves an award, but rather than for beating the law of averages, for beating laws of physics. 134 has only 85% of the cooling capacity of 12. Certain cars have enough engineering margin to tolerate such capacity loss, but many do not. I think Stan should buy a lottery ticket.

Have a great day,

Realistically, the only true proper conversion, is also swapping the compressor for one designed for R134a from the factory, if one is available for that model.
For cars made in the early 90's this is probably the case as most were in the middle of their model run. For older cars, you have to make due with what you have.

George

Gotta throw in my .02 here. In San Antonio we would regularly see temps >100 degrees and humidity over 90%. There is an excellent shop there that works ONLY on auto ac, and I will describe the info they provided me when I presented them with my converted Chevy Suburban.

For most cars, and smaller ones particularly, the r134 conversion would provide good "cooling" (with a reminder that a/c systems do not actually add cool air, but remove hot air and humidity from the cabin.) They said that some compressors and other components will work better with R134 than others, while some will work better with R12 by design. The R12 may cool a little better in some applications, but R134 would be just fine in most others.

It was suggested that for my non-functioning ac in my 190d (I wish I could get it from Chicago to San Antonio so they could work on it!)- it would be less expensive and cool just fine converted to R134, except on extremely hot days, at idle in traffic. On the other hand, my restored 89 Suburban with dual units and a proper R134 conversion simply doesn't cool well at idle in traffic in 100 degree temps in San Antonio. They said that the cabin is just too big for that particular ac system to really cool it on R134, particularly at idle. They said they would have recommended keeping the R12 on that application, but it would have been significantly (like several hundred dollars) more expensive. Since the conversion was done before we bought it we have learned to live with it.

Now that I think about it, I don't actually know anyone in San Antonio with an R12 system. That doesn't mean that it's not an excellent means of providing cooling, but I'd probably discuss the application, consider how much cooling is really necessary, and the cost involved before making this sort of decision. -J

My take on things....
 

The bottom line is this. R134a is not as efficient as a refrigerant as R12 is. It is much more enviromentally friendly, and does work well which is why it has gained widespread adoption.

Here is where things get more challenging. R134a requires more refigerant circulation to achieve the same cooling effects as R12. This is usually addressed in terms of a larger evaporator core (heat exchanger) which has more surface area, or higher pressures, therefore faster refrigerant circulation, or a combination of both. It's easy to design a system to work well with r134a, and there are countless sucessful examples.

Now, with a retrofit, you aren't doing that. You are taking a system engineered and designed to operate with R12, and introducing R134a. You can not change the size of the heat exchanger, OR raise the system pressure. This is why I mentioned that the only proper conversion is retrofitting all the parts to a factory designed R134a system, if possible.

The engineers who did the thermal analysis of the A/C system expected R12 in it, so that maximum cooling capacity would be to their specifications.

Installing R134a in one of those systems, will work, but will diminish the overall maximum ability of the system to cool.

A similar analogy is that of 87 (r134a) octane gasoline, to 91 or 93 (R12) octane gasoline. If an engine is tuned to run on 87 octane, such as a modern A/C system is tuned to run on r134a, it will operate fine.
If an engine is tuned to run on premium fuel from the factory, through the miracle of modern electronics, the engine will retard the timing to protect it, and it will run fine, but it will not produce the same power. For most situations is it acceptable, does it still run and drive?, absolutely, are you able to get the full designed potential out of it?, no.

Now, some A/C systems are overengineered, in other words people do not use the maximum capability on a regular basis. Think newer model GM here, those cars can double as a fridge. Others are adequate for MOST extremes, but adding in the diminished capacity of the system due to the change in refrigerant, may cause so so outcomes in these situation.

The other factor is that there is one a/c system designed for the model. I live in the Northeast, and experience maybe 15 - 20 95+ degree days per year. The gentleman from San Antonio, regularly experiences 100+ degree farenheit temperatures. There are no regional adjustments to the A/C to compensate for these differences. I have the same A/C he does. If it isnt that great on a 100+ degree freak day here, I will live with it. If it isnt that great every day all summer long, im going to be dissatisfied.

If your concern is maximum possible cooling and you like the car COLD regardless of the weather, you should probably stay with R12, it is still commerically available, but due to the epa restrictions, it is no longer a DIY task.

If you want acceptable air conditioning that will work to your satisfaction 90% of the time, want to do it yourself and for a lower cost, and not have to worry about future availabilty of refrigerant, an R134a conversion is probably the right way to go.

Take care,

George

very well said... :thumbsup:

agreed, very well said.

Also..... I have never been warm in an American car. I think it's one of those things that Americans demand is ice cold air.

Sorry, but the evaporator is not the component that must be changed to add cooling capacity, it is the condensor. Thermodynamics 301.

Have a great day,

true, he may have meant condensor instead of evaporator, but i think he nails it on why some people say it works fine and others are not satisfied.

So many opinions, just like an oil thread..... :juggle2:

Will it ever be worked out............. :P

Now we just need someone to step up for propane :eek:

Last I looked, the air blowing into the cabin came through the evaporator from outside. The inside air is blown out the vents because of the slight pressure rise caused by blowing cold, dry(er) air into the cabin. IOW, the A/C system adds cold dry air and whatever's inside gets pushed out.

It's been ten years since school and i'm an EE so I never really that got that far into thermal analysis. Need help with the electronics systems and i'm your man.

George

My education is in EE as well, but I grew up in my Dads shop. He started installing and maintaining auto a/c in the mid fifties. I was following him around then as a seven year old.

nglitz,

That's not what satyr is talking about. He is talking about basic physics as it applies to energy. Cold is simply a lack of heat. You cannot move "cold" you can only remove heat. Heat is energy and can be dealt with. Cold is nothing and cannot be "moved." This is one of the very first principles described in most any book on refrigeration.

satyrs main point is that cars are different with different parameters. Some have enough reserve a/c capacity to tolerate the loss of refrigerant capacity when switching to 134 and some don't. I agree with THAT PART of the 134 conversion philosophy.

The part that causes me not to convert is that statistically, 134 conversions don't last very long for various reasons. I have actually reverse converted some cars that I originally converted to 134, later failing for whatever reason.

Have a great day,

Two reasons to stay with R-12
 

There are two very important reasons to stay with R-12 in our cars: (other than the fact that R-12 performs better)

1. R-134A systems require 'barrier hose' to prevent them from leaking over time. The refridgerent molecules are smaller, and can diffuse out of systems that are not designed for them. They also require different seal material that is typically not compatible with the seals and o-rings spec'd in R-12 systems. If you look at o-rings for R134a systems, they are green and a different material compared to the black rubber o-rings that are in R-12 systems. R-134A will destroy the black rubber o-rings over time and leak by.

2. Lubrication: The oils used in R-134A systems and R-12 systems are not compatible. To properly swap over, the R-12 system should be thouroughly flushed out if you are going to convert, and some systems really can't be effectively flushed without dissassembly. But this isn't really the point. The point is that the R-12 mixes and disolves its oil better and carries more through the system as it runs. R-134A has a lower saturation concentration of its oil (it disolves less of its PAG or Ester oils) and thus carries less lubrication through it as it runs. This really equates to lower lubrication of the compressor that is designed to run with R-12 if you convert, and thus shorter lifespan. At the lifespan of our current compressors, I don't believe that it is worth the risk of lowering the lubrication even by a small margin. R-134A designed compressors have a slightly different design to compensate for the lower oil concentration in the refrigerant.

BTW, my background is mechanical engineering and thermodynamic systems design for nuclear power, but I have run into this issue before with other cars, like my old RX-7 that I tried to convert, and I did get the certification. I base my conclusions on my research of the issue both from engineering reference texts and automobile texts, and from experience of having performed maintenance and repair of both types of automotive A/C systems on many different cars I've owned over the years. I haven't had a single problem with the system on my 91 300E, but if and when I do, I'm going to repair it and recharge with R-12.

In the early days of 134 conversion it was said that barrier hoses were an absolute necessity. In the case of replacing a hose in a system that uses 134 this has turned out to be absolutely true. In practice, however, we have learned over the years, that a hose that has lived a few years in an R12 system has a film or buildup of oil such that it will not significantly leak in a converted system.

Thanks for the info Strider.

Have a great day,