Assuming you have electric fans, and the engine isn't hot enough for them to engage at the point when they're supposed to, the problem most likely lies in your thermal sensor.
to cool the coolant in the engine
the fans are operated by means of a series of relays which are turned on or off by the engine computer. the engine coolant temp sensor that sends its signal to the engine computer is what indirectly turns on the fans. if there is no check engine light for a coolant temp. sensor code, the problem lies in the fans themselves, or the relays and related wiring.
your themostat does not control your fans your fans are controled by coolant temp sensor if they are running all the time the problem is in the coolant temp it not working and ecm is overriding it and alowing the fans to run all the time.
radiator coolant switch, pcm coolant switch, relay , pcm , related circuitry or fuse.
check your coolant in your radiator northstar engines are designed to have your fans running if you have low coolant.
One fan should work when the A/C is turned on. Either the fans are defective, fuse is blown, or thermal relay is defective.
The electric fan must not be igniting when needed. When the motor reaches a certain temperature the thermostat opens and let coolant circulate through the system. However, the coolant also heats up and needs to be cooled at the radiator. When the car is moving, the wind from the motion causes the radiator to cool off, subsequently cooling the coolant. If the vehicle is running but not moving, the motor heats up and since there is no wind, the radiator fans are turned on to cool of the radiator. if your car has this problem it means the electric fan thermostat must not be working or the fans itself aren't working. Check for loose wires, connectors, relay and fuse before assuming is the thermostat or the fans.
Very possible your temperature sending switch is bad. If both fans work with AC, then it's also possible you have a wiring issue.
coolant temp switch or fan relay are bad.
No, the electric cooling fans turn on and off by a signal from the coolant temp sensor. The coolant level sensor only illuminates the low coolant light when you are low on coolant.
3 cooling requirements #1proper coolant mix and amount #2 thermostat #3 electric radiator cooling fans... fans must kick on when engine is hot, if the fans kick on and you have proper coolant level and mix, then it may be a defective thermostat, it's underneath the 3 in diameter engine fitting where the upper radiator hose connects to the engine . If the fans don't kick on could be fans, power to fans , or temp relay telling fans to turn on. Any ex stream outside temps or adverse diving conditions?
One can find information on Coolant fans many places. You can find information on Coolant fans from advertisements, such as commercial's. You can also find information online including there primary site.