I just finished my R&R of my A/C system on my 1986 300sdl. My compressor died about 2 years ago and I was only driving my car in the fall and winter because I am a procrastinator. I finally purchased a rebuilt Behr compressor, a R134A expansion valve, and a Behr drier, a new pressure switch and a new temp switch for the drier. I also purchased a bunch of new green O-ring seals, a can of pressurized line flush, one can of 12 oz. of a product called first fill which is R134A, a dessicant and oil, two 16 oz cans of R134A, and one can of Ester oil. As I have posted earlier the removal of old components was quite easy, even the removal of the expansion valve. But oh the install of the expansion valve!!! I found that if you extend the steering wheel all the way out, remove all components under the driver side dash and then move the driver's seat forward enough at its lowest setting for height, you can rest on the seat with your rt shoulder and work on getting the expansion valve back in. Attach the upper two connections hand tight, then the lower left and then the lower right. A crowfoot wrench is helpful for the upper nuts on the valve. Remember to put some ester oil on the O-rings and the fittings for easier installation.
By the way I used 6.5 oz of ester oil in the compressor which is what Behr recommended on an insert included with the compressor.
It was very helpful to remove all lower encapsulation panels and the side panel to get the compressor in and out.
I flushed all the lines with the cleaner and blew them out with compressed air.
I put everything back together and removed my KLIMA relay and started the car. I then bridged terminal 5 and 7 for about 5 seconds to energize the A/C clutch and get the oil circulating in the compressor.
I then pulled a vacuum for one hour and then let it sit for one hour and it held the vacuum just fine.
I then Installed the first can of R134A called First fill. I placed the can upright in a warm cup of water which helped increase the pressure in the can to fill the low pressure side of the system. I did this with car running, KLIMA installed and A/C on high and all the way cool.
It took a few minutes but once the freon started to flow into the system the A/C clutch came on and I was in business. I kept watching the gauges and it was looking just fine. I then added the second can of just R134A and also placed in in the large cup of warm water. I would shake the can a little and soon it was now empty. I installed the third can and it really started blowing cold in the car. I increased the RPM to about 2000 and the electric cooling fan came on.
All in all about 40 oz. of freon installed. Yesterday it was 84 degrees here with 70 percent humidity and vent temps at idle are about 45 degrees. I am very happy. I drove the car this morning and all is well, cooling well, no leaks that I can tell, BUT I will leave all panels off inside and under the car until I am confident that it is working well.

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John
1986 300sdl
1985 380se