See attachments.

 

Thank you for the detailed information. I am not very skilled to go through all these tasks. Can I just replace the a/c pressure switch without draining a/c refrigerant?
If not, I think this is not DIY job for me.

 

Hi skyrunner
There is no Schrader valve built into the AC pressure sensor port, unfortunately. I am currently looking to find or fabricate an adapter pipe that I could screw into the port with same sized threads and an AC gasket, and then screw the sensor into the Schrader check valved port for easy job next time.
I am currently stuck too with no AC. I have an iCarsoft MBII scanner and the AC screens describe the fault; first screen: low refrigerant but too high a pressure (indicating 70 psi when should be 30-38 psi) then next screen shows, when engine running and AC selected on that the compressor is not using any current (zero amps) and that the AC pressure sensor is open. Meaning the compressor is not electrically engaged, the 70 psi comes from the Hi and Lo side of the system starting to balance out. So don't go to car shop and get a recharge kit; the system has enough freon and pressure to run, just cannot sense it due to the faulty lo side pressure switch sensor.
Sensor Part Number 211 000 02 83 Location: you can see it through the lower LH side of the front grille. Three wire connector (ground, power and feedback for computer)

. You can see and touch the harness through the back side of the rad but cannot access enough to remove/service. The under belly pan must be removed. Then after of course fully service the AC, oil and R134a
Please do not remove the sensor at home and release the freon into the atmosphere. Mother Earth has enough issues on her plate. Let the shop capture it in their recycle machine. (Pic from a different Merc but clearly shows no Schrader valve)

 

Thank you for this my friend......