Your fan fuse could be blown, also check your head gaskets and engine cooling switch.
As for the water pump even if it's leaking it will still flow a little because your thermostat will still open and the shaft on the pump will still turn. Unless the car heads are all messed up.
When you replaced your temp sensor did you bleed the valve? It is usually on the thermostat housing. It is like a nut, or a screw on top. To bleed it, you do the following.
Make sure the coolant reservior is topped off with coolant (not the radiator, the reservior)
Warm up the engine to operating temperature.
Turn the valve on top of the thermostat housing slowly. Leave this valve open until coolant starts to trickle out. At this point you should have removed the air from the system. To be safe you can rev the engine a few times and repeat the process. If coolant comes out of the valve right away there is no more air.
Your vehicle could have 2 coolant sensors. One going to the Electronic Control Module the other going to the Instrument panel cluster, for the gage operation. The coolant sensor for the ECM is an input for the ECM & the ECM controls the engine cooling fans.The use of a scan tool is very helpful to diagnose this problem. A scan tool with output tests can activate the cooling fans in an output test, so you can determine if the circuit has failed or the controller.
The electric cooling fan operates when the engine cooling temperature exceeds a certain value. The cooling fan on this engine is controlled by the Powertrain Control Module (PCM). The PCM turns the cooling fan ON by grounding the coil of the cooling fan relay(s) when certain conditions are met. When the A/C is requested, the cooling fan will also be turned ON.
