I have an 86 190D and the AC has tanked. I want to change over to the new freon. What parts do I have to replace to accomoplish this job?


Asked by Mar 17, 2014 at 06:11 PM about the 1986 Mercedes-Benz 190-Class 190D 2.5 Diesel Sedan

Question type: Maintenance & Repair

I have an 86 Merz 190 D.  Over the years the old freon has leaked out.  I want to change
over to the new freon. I need to know what parts have to be replaced to accomplish this
job.  Some say that you need just the conversion valves and others have told me that I
have to remove hoses, concenser, dryer etc.  Your assistance is appreciated.

5 Answers


To do it right you need to flush the entire system so you can get out all of the old oil out, and replace the dryer, then grade the expansion valve to the new 134A valves, then evacuate the system to check for any leaks, add in the correct amount of Pag or Ester oil, split the difference between high and low lines, refill the system with the specified amount of 134A, that should bd about 80 percent of the R12 amount, when properly charged the pressures should be around 35 on the low and 125 to 150 on the high depending on the ambient temperature. This is kind of a general explanation but it will give you a basic idea.

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PAG oil is used for R-12, the hoses from r-12 systems must be changed for 134A because the new refrigerant is said to be able to emit from the old hose material. The new hose material is designed for a different chemical makeup at the atomic level, believe it, or blow it.


I have to disagree with you on the hoses, that is the text book talking, I have been doing the retros sense they started making the parts available, and the only hoses I ever replaced in all these years were the one that were obviously leaking before the retro. My preference on the oil is Ester simply because the corrosive quality is much lower that Pag and Ester won't cause a chemical burn if you get it sensitive skin.


They taught us the PAG oil was banana oil,(for R12 as I heard it) and the fittings for R134A were incorporated in our hose/accumulator setup, not for mercs but american cars. Their teaching to us was emissivity. so that WAS the textbook talking. They did say that the kit was going to be a very cost effective package to get everybody changed over, this is good info for me because the 190E Japan , in my yard, will need the 134A parts labor and gases retro'ed when I get the trans going. So whose parts are a simple set to buy? It took years to get where I am with all my trans/ clutch parts and info.


It was because my car was later identified as a '85 2.0L 190E with a 4 sp. used overseas, and my distributor was fixable for 20 bucks if I had known the first time I sought the correct parts. the trans parts were ordered from germany and were less than 50. The first estimates made me want to scrap it but they were all bad info. I then ordered a clutch during a sale at autohaus, and a flywheel ringgear. so, when it runs it will have lost its R12 from sitting. I wrote down all your info for the 134A from above, now i just need a supplier that wants to sell some goodies.

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