1998 W210 Air conditioning troubles
 

My air conditioning was serviced recently because I noticed it did not cool well, especially when the car was hot inside the vehicle. It would cool fine initially, then stop blowing cool air. A good local shop checked the compressor and system and said the system was fine , and there was no leak when they put dye in as well. I was told to look at the compressor when the cars seems to stop cooling, and upon further inspection, the compressor will stop engaging even when I still have the air conditioning on. What would cause the compressor to disengage like that????

LP

It could be the evaporator temperature sensor. Search for that here, and you'll find the procedure to extract the current-sensor values from the pushbutton unit.

refrigerant pressure???
 

You may be right on the cusp of recommended pressure. Not a guarantee, but when the pressure sensor detects pressure below the desired level it will disengage the compressor to prevent it from burning out, likewise I think it does the same if overpressured (maybe when hot you exceed the upper range)
pv=nrt.

I think you can check this from the W210 climate control by going into diagnostic mode, I have yet to try this but you need to press the reset button for 5 seconds while the key is position 1 or 2 prior to start up. Search the forum, I'm sure someone has posted the correct way to enter into this mode.

good luck

Mine has a leak and it's the big one, I read the diy and it's scary, too scary for me to attempt just yet.

It would not "cool fine initially" if the refridgerant level is low. The left side will be warm. Also, since the pressure sending unit is on the high side, it won't show too low once the compressor actually engages.

I still vote for the evaporator temp sensor. It's a common problem on the 210, and easily identified as the culprit when in current sensor mode (it's #5).

Do a search, and replace the ETS first - symptoms sound about right, and not too expensive. I agree, low charge results in one side blowing warm which would be readily apparent.