Thermoswitch for the cooling fan.

[Howarth1 at aol.com]

Which sensor is the one for the radiator cooling fan on a 1990 model 100 (2.3 SOHC).  Where else should I look if the fan will run on low with the A/C in Auto but will not kick on in econ as the temp gets high? Does that thermoswitch have two threasholds, in other words, how does the fan get the signal to go from off to med to high?  Thanks.

Richard Howarth
1990 100
1990  90
1986 4000
1986 5000 CS Turbo