Also, don't know where you're located, but in most cars, its unusual
for the aux electric fan to come on unless it's very hot outside and/or
the car is stationary or in slow moving traffic.   Normally the regular
fan should provide adequate cooling.  I had a problem once on my 300SD
and part of the circuit was turned on by the A/C being on and the
refrigerant temp at the radiator being over a certain temp.  It was
controlled by a relay.  There's probably another part to the circuit
that turns it on if the coolant gets too hot too.

Thanks guys!  I appreciate the help.

Thanks for all the help on this one guys.  I changed my temp control
sensor and tested for current; the motor temp was checked and turned
out to be o.k.  A/C wouldn’t kick on fans because there was not enough
pressure in system to activate it.  Turns out there is a bad
connection in the cluster and temp is reading erradic.