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Old 05-14-2001, 11:59 AM
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Join Date: Mar 2001
Posts: 40
I have an 86 190e16V that the A/C does not work any more. Instead of fixing the existing system I would like to convert it to the new 134 system. Can someone please tell me how to go about doing this? Thanks alot


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Old 05-14-2001, 01:45 PM
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Join Date: Apr 2000
Location: Falls Church, VA
Posts: 5,316
Do a search on R134 and you will get a ton of information. There was a dialog on this about a week ago.

Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
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Old 05-14-2001, 04:35 PM
Wm. Lewallen
Posts: n/a
You can get the conversion kits from Autozone, Advanced Auto Parts, or other parts stores. They contain everything you will need to make the conversion and they cost $34.95.
Bill Lewallen; Lexington,Ky. Home of Valvoline Oil...
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Old 05-14-2001, 04:54 PM
MikeTangas's Avatar
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Join Date: Apr 2000
Location: So. Cal
Posts: 4,430
If there is a leak or other problem, you will have to fix the existing system before you can convert.
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

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Old 05-14-2001, 05:00 PM
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Join Date: May 2001
Posts: 165
R-134a conversion

I would recommend the following:

1. Change to a R134a compatible compressor
2. Disconnect every line and change o-rings to R134 compatible o-rings.
3. Flush the lines, evaporator, and condenser
4. Install a new dryer & expansion valve (if system uses expansion valve).

The R134a oil is not compatible with the R12 oil. It is my understanding the 134a will destroy the R12 seals if they are not changed. Also a R134a compressor is more efficent at compressing R134a.

I converted my 88 Saab 900SPG to R134a a year ago and it blows ice cold. My 87 300SDL is still blowing cold so I haven't converted a MB yet.
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Old 05-14-2001, 06:15 PM
Posts: n/a
It's as Simple as Falling off of

Brother of The Benz
Alex, as mentiond if you have a leak in your A/C it must be repaired.
In finding the leak it is cheaper to pressurize the system using $5.95 per can of R134A than $40.00 per can R12.
You will recieve a ton of how to do it from the replacing of major components and "O" ring seals to the Gas Tank Cap.
I have a 1987 W124030 that is running R134A and I am very pleased with the performance of the Refrigirant.
Changing to the new gas is simple.
You will need a Kit that can be purchased at all auto parts houses as well as K-Mart, that's where I get my supplies. In addition a manifold gauge set and hoses.
You purge your system of R12 using a recovery system provided by your friendly A/C service center. I don't know what they charge where you are for this service. I know of others who just vent the gas to the atmosphere but you do what you think is right.
After repairing the leak, evacuate the system using a vacuum pump. There has been different opinions as to how long and to what pressure to pump down to. I will say that pump to the blank off of the pump and a little time more.
The conversion kit comes complete with compatable oil charge, 3 12oz. cans of R134a, a can tapper, new service valve fittings, and a service hose.
With the system at minus pressure you add the oil charge first, then the R134A gas.
You reduce the quanity to 75-80% of the R12 capacity. If your system used 3.5lbs. of R12 you would charge using 2.625-2.8lbs. of R134A. The capacity of the R134A can is 12oz. For 2.625lbs(42oz) would require 3.5 cans.
That's all there is to it.
You probably won't be able to tell the difference in the cooling between to 2 gases, I haven't.
Place the labels noting the system is R134A and you just made a conversion.
Listen to all of the different ways you will be told of and then make your choice about this very simple and inexpensive job.
Happy Trails Beep Beep from The Spiderman in Houston!!!
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Old 05-14-2001, 07:13 PM
Join Date: Jan 2000
Location: Maryland. USA
Posts: 180
Old Oil removal.

I've read a fair amount about the need to remove the oil and don't doubt it. However, How does one go about removing the old oil without contaminating the "New" Receiver/Dryer?

S, J.R. Brown
2000 G500 LWB Obsedian Black
2005 Toyota Tacoma Access Cab Off Road Sport
1993 Volvo 240 Sedan Anthracite
1980 450SEL Champange (owned it for 15 years. Great car)
1986 280GE LWB Anthracite (Sold it and kinda wish I hadn't)
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Old 05-14-2001, 10:48 PM
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Join Date: Apr 2001
Location: Baton Rouge
Posts: 485

I retrofit systems from r-12 to 134a . A little advice
1. Check compressor pressures, if you have pressures that fluctuate , replace compressor with new not rebuilt.
2. If compressor is ok , you should know that converting your system ,the air will not be as cold as r-12. It usually cools 15-20% warmer at idle.
3. Replace reciever drier and flush system. Do not vent your r-12 (the fine is very hefty). And yes fix the leak .
4 . I dont replace all the o-rings I have never had a problem with leaks but it doesn't hurt to run a leak test afterwards.
5. Now for system capacity, dont go by sight glass. Your system usually holds 2.4 to 2.6 of r-12. Now you want roughly 15% less than that so start at 2.0 lbs. Add while watching your pressures. I like to add in the heat of the day when it is hottest. You want your pressure yo be 35-38 low side (blue side) at idle. High side start off around 180-200 . As high side increases low side will also a little but when auxillary fans kick on pressures will drop.
But to let you know just like I tell my customers these compressors ( nipindenzo) dont cool well at idle with 12 in so dont expect it to cool like a new mercedes. Now the R-4 and a-6 compressors cool good . The only ones I recommend not to retrofit to 134 are 107 and 124's . Its a 50/50 on those cars .
euro 287
Mercedes Technician 7 Years (retired to Hyundai)
2000 Dodge Durango
98 Mazda truck
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Old 05-15-2001, 12:00 AM
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Join Date: Feb 2001
Posts: 631
I have some R12 that I need to sell. I don't have anything that uses it anymore. Reasonable. E-mail me.

1995 S-350

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Old 05-15-2001, 03:23 AM
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Location: PA
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What is your e-mail address?
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Old 05-15-2001, 02:10 PM
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E-mail me through shop forum.
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Old 05-15-2001, 02:52 PM
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Join Date: Jun 2000
Location: Saugus, CA USA
Posts: 2,022
If you have your old R12 sucked out by an AC shop, can you sell them what they get out? As expensive as R12 is they might end up paying you to empty your AC.
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Old 05-16-2001, 10:25 AM
Posts: n/a
So Many opinions

Brothers of The Benz.
I don't know where this information about the conversion to R-134A has come from. It had to be originated from a very accurate source.
Here on the gulf coast the conversion is as simple and inexpensive as I posted.
There is always the question of oil compatability. The new oil blends with the original and the blended oil satisfies the oil requirement. Also in this new oil is an "O" ring conditioner.
As for removing the oil in the components, Condensor, Evaporater, Drier/reciever and the compressor, they will require removal and drained and flushed clear.
Boy what a major job that would be.
I'm not going to try to persuede you to do what you feel is detrimental to the long life and cooling ability of your A/C.
From all the data I've collected prior to my conversion, the "El Cheapo" vs. the very expensive and not needed process functions excellently and with a temp drop of no more than 10%. The method given to you by others is felt to be accurate by the giver.
In summation, all I have to say is,Talk to others who have made the simple conversion and the other elaberate type and "Do what you feel is right, and be happy in it".
Happy Trails Beep Beep from The Spiderman in Houston!!!
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Old 05-16-2001, 10:42 AM
Posts: n/a
Converted almost 100 R12 systems to 134a with the 35.00 kits with no mods other than what the kit provides. And with no long-term failures due to conversion either!

Sure you can be political correct and flush the system, install orings yadda yadda yadda... Just do it the olde fashion way.

Step 1: fix the leak if there is one.
Step 2: install the retro-fit 134a fittings
Step 3: Evacuate, install oil charge provided and charge the system.
Step 4: enjoy cold A/C

As far as discharge temps, I have found no difference noticeable. I had put over 70K miles after a retro-fit on a 93 Dodge van with no failures. And My 74 280 works great down here in Florida after conversion !
The Spiderman is Right!
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Old 05-16-2001, 12:57 PM
Posts: n/a
Tune into Channel!

Brothers of The Benz, Channel1.
I thought I was the only one that made the conversions as the instructions with the installation kit.
I truely feel for those who take such extremes for a simple and inexpensive item. And after the high dollars spent don't cool any better or last any longer than yours or mine.
I might add, that after installing the ester oil, my compressor is quiter.
Oh well there will always be the purest even if in the misplaced.
Happy Trails Beep Beep from The Spiderman in Houston!!!
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