Atif Sarfraz

Hi,

I'm working on a car C217 2018 model( S-Class coupe 400 4matic) which was imported from a European Country ( according to star diagnosis) which is equipped with a new generation gas R744a(CO2). The car was imported to a middle-eastern country (Qatar). And the customer has complaint the A/C is not cooling as it should.

Things i have done till now are the following:-
1. Change the country code of the control unit from European country to Gulf state). This setting improved the cooling still not at good as it should be.
2. Updated the control unit software. ( still the same )

I have also tried this cars A/C control unit in a car which was equipped with R134a and updated the software to make it work. And the cooling worked like a charm. Installed the other cars A/C control unit into this and it was same state as with its original control unit.

My question, is it possible to change the R744a equipped to r134a? If so what changes should be made ?

The customer did take the car to the official dealer here in Qatar, and they didn't have the particular refrigerant gas. The only gas they have is R134a.

Looking for anything that can work or help in converting the cars A/C system to R134a .

Thanks.

wbeeton

I am a retired engineer who worked on ac systems and am familiar with both R744 and R134a. The short answer is that a conversion is likely impossible, because the characteristics of the two refrigerants are so different that the entire system would have to be changed out; however, the physical geometry of the engine compartment as well as other system considerations means that even if physically possible, a complete system change out would likely not function. Furthermore, even a well-functioning R-744a system will likely not work in the Middle East because R744 does not work well at high ambient temperature. This of course is up to the factory, but i doubt if they are using any R744 ac systems in vehicles destined for the Middle East.
I'm very sorry for this answer, but i think that if the owner wants a Benz with adequate air conditioning, he will have to buy a Gulf State destination vehicle designed for R-134a.

Sameer Ali

Dear Sir/Madam,

well i have been struggling for Mercedes S560 S Class European Spec Car where the AC GAS R744 is coming in the car unfortunate this GAS Is not available in UAE and we are having tuff time for struggling this gas i want to change the complete system like compressor and all other accessories where my car can become GCC specs or any other spec where i can fil R134A Gas easily - I need to change complete unit computer as well completely so i don't face issue using R744 GAS.

please help me out with some diagram or some video or components where i can change the system including compressor which takes R134A GAS

Many Thanks,
Sam
+971505282027

Warren Beeton

I'm very sorry, but i cannot help you. Converting you S class to R744 would be very complicated, and only Mercedes Benz would have the technical ability to help you -- but they may say its impossible to make this conversion. The R744 gas is nothing more then carbon dioxide (CO2) -- if your ac needs servicing, you need a Mercedes dealer who could charge your system with R744 -- but such a dealer may only be found in Europe, or in some neighboring country

grabbou

Did anyone figure out how to do it?

Here's the thing... my R744 installation is broken and it is going to cost a fortune to repair (dealer only work, no parts available and expensive equipment required).

North America C217/W222 face-lifted models have R134a, whereas European spec has R744. I believe Mercedes must have done some shortcuts and at least electronics should support both systems. I need to replace everything anyway, so I'd rather buy the parts for traditional conditioner.

Warren Beeton

I have no idea how an R744 a.c system could be replaced with an R-134a system in an auto. The systems are so different that I'm skeptical it's even possible. Sorry I cant help you

VII

Yes of course it is possible you have W222 variants with r134 so the exact parts you need are readily available.

The list of parts you'll need are likely:
Compressor
Condesenser w dryer
Evaporator
Expansion valve
Lines
You can check the variants in EPC and determine which parts are r744 specific to get the exact list.
​​​​​​

Jud Chapin

FWIW, R134a is being phased out in the USA which started a couple of years ago with certain new vehicles.