As stated you have a two speed fan and the first speed is almost always on if its hot out and you are using the A/C. It comes on when the A/C gets to a certain pressure (which it will always do unless you are low on refrigerant).
There is no 212 switch on this guy. The A/C system turns the fan on for both refrigerant pressure and engine temp.
Bosch Master, ASE Master, L1
33 years MB technician