how hot is the car getting?
Be assured that gm thought it would be a good idea to only let the fans go on when the temperature exceeds 212*. If the car does not get about 211 the fans will not turn on.
if there is a problem with the fans it could be:
COOLING FAN CONTROL MODULE
Part #: 009361735
as far as the coolant temp sensor, not 100% sure where it is on your L36 but on my motor it is on the back of the engine on the right side near the the throttle body, It is bolted to the lower intake manifold.