AC Question/R12 vs R134
 

My '86 560 SEL has the stock AC system with R12. I have always recharged the system every 5 years or so and always with R12. Today when I went to my indie MB shop that I have been using for many years they told me they were going to use R134 for the recharge. I asked how was that possible as everything I have ever read about AC systems says you cannot charge with R134 without making many modifications. The shop owner assured me that R134 would not hurt my AC system. I told him if there was a problem adding R134 to the system he was going to have to fix it. He said he would fix any problems and again assured me that everything would be OK.

Comments please.

if you want a/c that will only have 70% of the power of the r12 go right ahead[after flushing out the old oil and replacing with oil compatable with 134] and don't forget that because the molecules of 134 are so tiny you will need all the hose replaced with barrier hose or look forward to a recharge every year.

Your indy is wrong, I would go somewhere else for a/c work from now on, or insist that he use R12.

To begin with, you have to flush the system to remove all the old mineral oil, then replace it with the newer synthetic oil that is compatible with R134a. Then, you have to change all of the refrigerant hoses in the car, or else you're going to need to recharge the system every time you turn around, as the unlined hoses in an R12 system will allow R134a to escape easily. R134 requires lined/coated hoses.

And if the cost and aggravation of all that isn't bad enough by itself (it is), then be prepared to have an a/c system that only works half as good as it used to. R134a is less efficient than R12. The 134 will never come anywhere close to the performance you are used to out of R12. If you live in a hot climate, you will not be happy with the result at all.

I would absolutely NOT make this switch. It's not going to give you the performance you're already used to. As another member said, it will only work maybe 70% as well as the R12 did, and I think he's being pretty generous when he said 70%. I've had both 12 and 134 in my W126, and I would personally say the R12 worked closer to 2x as good as the 134. And the part about being able to just suck R12 out and put R134 in, without doing anything else is just wrong. I mean, yes, physically you can do that, but it's never going to work right. Your guy doesn't sound like he knows what he's talking about when it comes to conversions.

Where can we find out how many cans or ounces of r-12 is needed to recharge an empty system?

most of the older r12 systems held 30-39ozs of refrigerant so between 2 1/2 and just over 3 cans.

Thank you David.

In reviewing my service records I found an invoice from 2006 for an AC recharge. At that time I assumed they would use R12 as that was what was in the system. Wrong!!! In the fine print on the bill I noticed I had been charged for R134....it appears I have been using R134 for the past three years and did not even know it. I called the owner and let him know how I felt about them arbitrarily switching to R134. I would not have let them do it had I known. I told him I was holding him responsible for any damages that may occur to my AC system. I have been using this shop for almost 15 years and they have always been very reliable, honest, and reasonably priced. The original owner sold the shop about three years ago to his service manager who is the owner who I spoke with today. Looks like I am stuck with R134. I will keep a close watch on the AC...it is blowing cold air today. I have a hunch that within a year my indie dealer with be doing some "warranty work" for me. He has been put on notice. I know he does not want to lose me as I have been a valuable customer to him for many years. I'll let you guys know how it turns out. Thanks for all your input.

Ive been considering trying out one of the alternatives to r-12 and r134a

Did you notice the difference with the AC running on R134a without knowing it? It would be hard not to notice if R134a was at 70% or 50% efficiency as some members pointed out.:confused:

Thinking back, my MB never had really cold air...and I think that is pretty common, at least on the 560 SEL models and other models of that era. But yes, it did seem to me that the AC was even less cold for the past few years since the R134 was put in. I probably rationalized this as just standard MB "not very cold AC". After they recharged the system today the air was blowing much colder than it had been....probably because the system was low on R134 because of the slow leaks through the R12 hoses as has been mentioned in this thread. Needless to say, I was not happy finding out that I had been converted to R134 without my permission.

R12 alternative FYI
 

From what I have learned R134A is a very poor replacement for R12 and to make matters worse it is only marginally better for the environment. When you factor in all the botched up AC systems that some (not all) users end up with, much of this stuff ends up in the atmosphere....much more than properly maintaining R12 systems. The host of other Freon blends are also cr@p for the most part IMO.

My 92 w124 had R134A when I bought it for my wife and it had the condenser blow and that was the end of it. Head pressure is greater than that in an R12 system.

I searched for a Freon replacement for my 90 w124 and tried Red T? it was garbage and did not cool at all though we followed installation/conversion instructions to a T.

I searched some more and found SP34E {Liquid charge ONLY} {80% to 90% of R12 charge} for me it was a direct R12 replacement. The system was properly evacuated and charged, it works very well but it has only been in for one year.

I do think that many AC systems are damaged when some people who lack proper tools, equipment and experience try to work on or diagnose rather complex AC Systems. I have also heard QUOTE " my buddy fixed my AC, he knows a lot about cars but now it doesn't work eh?

I didn't actually mean to write all this, oh well,
Acky

The 2 alternatives I have heard the most good stuff about are freeze 12 and Envirosafe ES12a

My son, a mechanic for 30 years, says that Freeze 12 is totally compatible with R12, and works just as good. I still have about 6 lbs. of R12 so haven't tried it yet. I did switch my Jeep from R12 to R134, and as said earlier, it's barely half as good. My son said that if they don't change the compressor oil (which many don't) it will be worse yet. Only remedy is to flush, reservice with the proper oil, and use the corresponding freon.

From what I've read, HC blends work well in R12 systems, although not quite as well at idle. Better at idle than 134a, I'm sure.

The problem with HC blends is that it is illegal to convert directly from R12 to HC. Since mineral oil is miscible in HC liquid, it would be ideal to extract the R12 and charge right up with HCs. It would be better for the environment than 134a. But it's illegal and the penalties are quite severe.

Not sure why anyone needs to convert to R134. R12 is getting cheap these days as fewer cars are using it. I have 4 cans on Ebay for $80.

R134 is the only alternative to R12. Anything else will be a gamble and no shop would knowingly touch your system with a recovery machine if they knew you had put some sort of snake oil in it.

Before anyone says Freeze12.... Freeze12 is 80% R134 so it's not a direct drop in as it's 80% R134 so it won't mix with the oil so R134 is the only real alternative.

The recharge connectors are different between R12 and R134a. R12 are screw on, R134a are pushon similar to air hose connectors.

If the car was converted to R134a, the expansion valve would have been changed as all the O-Rings. There would be a blue lable with a date on it.

You cannot add R134a to an R12 system.

http://freeze-12.com/

http://www.supercool.ac/intro2.htm

http://www.acsource.com/index.asp

http://dieselgiant.com/index.html

A DIY page

http://dieselgiant.com/repairyourac.htm

In response to the questions about how many cans of Freon. In the past you would just view the sight glass and watch the bubbles. When the bubbles went away, it had a sufficient charge of Freon. If you suspected the Freon was low, you just looked at the sight glass.

Has it changed now for the older cars with Freon? My 81SD has a sight glass and still runs Freon and feels like a meat locker.

This is the method that I use with R12 systems. I don't think that it applies with R134 systems or systems that have been converted to R134. You're better off hooking up the pressure gauges and making sure that it's filled to the right pressure.

Put it in an MB (such as this 560sel) after running R12 and let me know what you think. It doesn't cool nearly as well, especially in a volatile climate. Well basically from the middle of the 48 on down.

These cars were designed in Germany, ever checked the latitude of Germany vs the US? :eek: :D Hot days to them are not hot like they are here.
Girlfriend of mine lives outside of Moscow, how to her is in the low 80°F area. That's downright pleasant to us.

MB updated the AC systems constantly in these cars just like BMW did with the E23s of these years. The condensers early were inefficient, so they doubled the tubes for more surface area to dissipate heat (same capacity) around 1985 from what I gather, the aux fans were tiny on the early cars (again, became far larger) these grew around 1984, heck then in 1989 AGAIN MB changed the condenser fan and went to dual fans.



Can't agree more. I tried F12 in my 300sel only because the system supposedly had an evap core leak, it doesn't. So I need to... uh.. have it recovered then recharge it with R12. Cooling is very poor with it unless running down the road, then it's decent.

I have multiple tanks of R12, it's just NOT that expensive to purchase in large quantities (sub $10/lb... that's nearly on par with the 134A at the auto stores). Hell, even like what Al is selling is plenty reasonable @ about $25/lb... a properly rebuilt system shouldn't need an AC service for easily a decade. I'd buy two, maybe three setups like Al is selling and be covered for a while if I had to have my car serviced somewhere.



LASTLY, you guys doing AC work in the summer are going to get reamed. This HVAC stuff needs to be done in the off-season so demand is low and you'll get better pricing on parts and/or labor.

I got tired of the wondering every season if my A/C was going to need work in w126 and had my entire system gutted and professionally converted to 134. Every part of my system was replaced including the compressor and anything that touched freon such as hoses and other parts. I decided to do 134 because its more likely to be readily available in the future and with replacing everything I had the opportunity to do a proper conversion. My A/C is ice cold and comparable to the A/C in my w140 even though the w140's system is a superior design.

I think a lot of the misinformation about 134 is due to leaky systems that people just put a charge on without completely sealing and cleaning the system. The unfortunate truth is if you want really cold A/C your going to likely need the assistance of a professional that's able to correctly seal your system and get any moisture out of it with a vacuum pump. Pumping 134 into a leaky system with moisture in it would have a similar effect to doing that with R12.

People who willfully pump R12 into leaky systems because of cost are the reason why we had to change to 134 to begin with. Karma is a wonderful thing though. That moist sort of cold air must be great eh?

And what are your vent temps on 134? Idle and cruise?

How many thousands did you spend to do this? Two? That will buy you nearly a few hundred pounds of R12. Will you actually be driving that car in 10 years? 20 years? Probably not, but maybe. A 30lb tank of R12 would last that car pretty much until you and I are not able to drive anymore.

I used F12, basically 134 with a few other bits within. System was totally rebuild last summer by ME, including expansion valve, orings, compressor (obviously), etc. The performance is decent when cruising, but lower speeds it just lacks big time in the 300sel... I have R12 in my other stuff, I'll compare to my MBs only for sake of discussion, in my 300SD, SDL, and 560sel, the performance is just far better due to the limited capacity these vehicles have to begin with. Going from 2.9lbs to 2.3lbs is a large drop in capacity... this is because, 134A is less efficient! New vehicles have updated condensers/evap cores to compensate.



Aside from certs, I think there are more than a few people (including myself) that have the knowledge and skills, and own the tools, to properly rebuild an AC system on these cars and others. I've rebuilt close to a dozen now (stuff from the early 70s to mid 90s), there's not much to them. It's like assembling an auto trans or building a valve body. Take your time, keep it clean, and be patient. Biggest of all, don't rush or use crap parts.

I rebuilt the one in my '88 F150 back in 2000, it's still working great to this day. This was my first one done.



The mandatory conversion for auto makers to 134A is largely debated, it's more than ozone depletion... 134A does almost the same job at depletion FYI. Dupont's patent expired/was expiring on R12 in that time frame too FYI.

Have not really had the need to measure the temperature. At least as cold as my W140's A/C if not colder. With the temp set to 22 on the wheel the car cools as quickly as my W140 even after sitting in the sun (both of my cars are black).

I have owned the car for about 7 years and plan on keeping it for a very long time. Recharging year after year and wondering if my A/C was going to make it though the summer was getting quite old. The system in the car was 27 years old and really needed replacement.

The cost was more reasonable than I expected but the figure is between myself and my mechanic. If I had known I would have seen this level of improvement from an overhaul of this level I would have had it done 7 years ago.

When you consider the cost think of how much it costs to diagnose and repair a system every few years versus doing it right and having a better performing more reliable system. While some people have the false sense of savings by doing their own work how much is your time worth?

I don't think anyone here is suggesting using R12 or any other refrigerant in a system that is known to leak. That's like throwing away good money after bad money.

Problem is that a half done conversion to R134 or any of the snake oil on the market is that it will probably create leaks in what was otherwise a good system.

You got sold a bill of goods, man! R12 is still being produced overseas, you just can't make it in the US anymore. The whole "it's going to run out" in the future thing is total B.S.

And R134 isn't any better for the environment than R12, it's also highly toxic. I'm not really sure what the government thought they were doing when they started forcing the switch. In any event, the government has really backed off the whole R12 ban thing anyway, they don't seem to care about it now. It takes 30 minutes to get a refrigeration license online and buy and install it yourself. All the a/c shops around my area have no problem dealing with it either.

Not at all. I won't be under the hood next year trying to figure out why my A/C is lukewarm. I overhauled my system mostly because it was tired and 27 years old. Picking a modern refrigerant that has a higher probability of being easy to find in the future made sense for me. You can get R12 now but what about 10 years from now when many of the R12 cars have died off or have been converted? I plan on keeping my car long term.

I converted to r-134 but I do not like the results. What is the minimum I would have to do to go back to r-12 and have it work?

Perhaps not intentionally but with limited tools and budget many shade tree mechanics are doing just that. I assume everyone here has their own R12 recovery systems and vacuum pumps right?

I think you hit the nail right on the head. In order to convert correctly to 134 parts need to be replaced and money needs to be spent. The shade tree approach of charging with 134 and slapping a sticker on under the hood does not work quite so well.

As the owner of a '93 2.3 and still using R12, what procedures did you perform when you converted to R-134a?

I believe my system was empty when I bought the car. I put in a new drier, new fittings, new oil, new freon and a new label around 4 years ago.

Thanks for the reply,

I've heard from other forum members that have had good/decent luck converting to R134a by basically doing what you've described, including vacuuming the system. One important factor was putting in the correct amount of R134a, since using the drier sight glass isn't the right way.

Bring your car to your local mechanic and have them recharge it for you. Regardless of the coolant R12 or R134 your going to see an improvement getting all the air and moisture out by having them put the car on a vacuum pump.

I don't assume that everyone does but i do :). I actually bought my recovery machine for $50 on CL. From personal experience, I know that these old barges can have good working A/C using R134 provided that the conversion is done correctly. One of my 6.9's was converted by the PO to R134.

From what I can see, it has a new compressor, condenser, hoses and the aluminum body ACCII unit. It will turn your fingers blue. The job was done correctly and he must have spent thousands on it.

The reality is that with most of the cars that we drive, this can be cost prohibitive as not many people will drop $4000 replacing every A/C component in a $1500 car. I guess the point that I am making is that if all you need to do is replace a seal or a compressor, it may be more effort then it's worth to convert to R134 when R12 is still pretty cheap. I do feel that if you are going to convert, it should be to a standardized product like R134 and not to anything else. Even when I replaced the condenser on my other 6.9, the box clearly stated in bold red letters that the warranty will be voided if anything other then R12 or R134 is used.

I'm really glad to hear you do your own recovery but keep in mind you are probably one of the few.

The reason why so many of these cars survive is because of owners that are willing to write the checks to keep their cars going. If you sit down and do the math everyone spends more than they paid on service and repairs to keep their Mercedes going over their ownership if they are not the typical use it up and quickly sell it before you have to repair it. The glorious trailer trash looking for a bit of style and attention that would be driving Hondas if older MB's were not so cheap. $4000 over 10 years of ownership is only $400 a year, $33 a month for a beautiful car with brutally cold A/C. Seems pretty cheap to me! Depending on the condition of the rest of the car a potential selling point to a buyer knowing that the car they are buying had an expensive upgrade. Well sorted 6.9's do fetch a tad more than $1500.

I do agree that poorly done 134 conversions work but are horrible. I have test driven cars with backyard 134 conversions and enjoyed the humid semi cool air blowing out of the vents with the fans running full bore. Total Crap! I would rather roll the windows down and at least be able to breathe. :)

To put things in perspective the Porsche 944 I just bought has a recent receipt in the glove compartment for a $6700 visit to the mechanic. Easily double what the car was worth in one service visit.

I've got receipts like that for my 750iL too (last was summer '05 for $5800 or something insane), but.. it's still R12.

Honestly, that stuff will be around until we're all forced to drive non-internal combustion vehicles. Just doesn't make sense to me to convert it when the properly working R12 is great. I got my R12 machine up in Porter (where most of my tools are/workshop) that I too got on CL for sub $200. As I stress to people, buy HVAC stuff off season.

Just seems like you're not the DIY guy at all (which is fine, we have plenty of enthusiasts here that don't like to get into it for whatever reason), so the conversion can/does make more sense. I enjoy operating on my vehicles, if I didn't, there'd be zero sense to keep these all around. It's not my career, nor do I make cash off it. Just my way to relax, have a good time, and keep me out of trouble.

Hell, part of the fun is scouring for the odd parts or the odd car and bring it back from the grave.

I used to do a lot of DIY stuff. A busy work schedule and lack of time sort of killed that for me over the years. A lot of my DIY work has evolved beyond cars as well http://www.systemv.org/site.html . I still like to have a complete understanding of how the systems on the car work. I'm also really lucky to have two really super honest super reasonable independent mechanics. I enjoy making them a buck and keeping them around as they have saved me a TON of money over the years keeping me away from the evil lying manipulating dealerships.

Ironically in the trunk of the car I just did the conversion on is a brand new unused compressor and receiver dryer and other parts that I bought planning to do some of the work myself.

R-12 question
 

I have disconnected my A/C after the bearings on the tensioner went out. Getting that part was expensive. Now I am going to put the belt back on and take it to get recharged. So, after over a year, the A/C compressor is about to be connected to a belt again. Should I have the shop connect the belt or will it be fine to put it on myself and drive it in? I just paid $200 for a little pulley so I want to try and save myself some $$$$.

Any thoughts...espeacilly from Mr. Pool....lol...you probably don't remember me, but you serviced my little BMW 325i a long time ago:P

Does anyone know if the SEL received a condenser upgrade in 85-86 timeframe like the SD W126? I ask because I believe my '89 560SEL has the older style 'large tube' condenser. Not nearly as many tubes as my '85 SD's condenser.

Looks as though there was an upgrade on the gasser W126 also.

Gen I A126 830 2770, Gen II A126 830 2870.

I suspect my car has had a Gen I installed as a replacement at some time.