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

__________________
Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.

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.

__________________
With best regards

Al

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.

__________________
With best regards

Al

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

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1990 560 SEL- "Goldielocks"
1984 300SD TurboDiesel- "Ole' Blue"

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.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

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.

__________________
With best regards

Al

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.

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.

__________________
With best regards

Al

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.

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?

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1993 Benz-190E-2.6 liter