Originally Posted by jbaj007

It's a simple on off switch set at ~40ºF, with ~ 4ºF range between on/off set point. There are two screws in there once you get it out, and get the plastic cover off. One screw adjusts the set point (works the large spring) and one adjusts the range by tensioning the points that act as the switch contacts. Mercedes says not to adjust them, but.........

I am currently experimenting with a regular refrigerator thermostat instead of the Mercedes ETR (it's the same thing as the ETR, only cheaper) that is adjustable while driving (being careful contorting under the dash ). I'm trying to get it as close to freezing as possible without icing the evaporator, Again, a simple on/off switch that turns the compressor off when the evap gets too cold.

I run a parallel flow condensor, aux. fan relayed to compressor, with a "test" refigerant and freezing the evap is my problem. Quick cool down after parked in the sun is my big deal with airco and it's difficult in our old cars.

Good luck