Refrigerant temperature Sensor
This must be a weak part as the one in my '97 E320 has been replaced twice. iI plugs into the evaporator which is under the center of the dash. Call Phil at PartsShop. he can help you get the latest version.
Last week I put out a querry here about what kind of A/C problems people were having with W210 cars. I don't find much on this site. Is that to say that the system in those cars has been relatively trouble free? Thanks.