Crown victoria 2003 cooling fan run on never turns off. were is the cooling sensor located? radiator? engin block? manifold?

You'll find said sensor on the lower radiator tank. Just look for a wire connected to a sensor screwed into the lower tank and that's it.

Sounds like you have a double problem . First locate the radiator fan relay it should be in the fuse box change the relay. Also change the tempature sending unit (attached to radiator) . If your car is overheating . You need to check. For a leak, be sure you have enough. Fluid in radiator, check. Thermostat , change it anyway cheap enough, ( 16 lbs. pressure ) this should solve your problem

I would check my relay's and or your fuses first. If thats not it, let it cool down and take it to Auto Zone or somewhere close to have a diagnostic readout done. Good luck.

If the sensor was the problem you would have a check engine light on, the fan is operated by the powertrain control module which controls a relay module. You must have the dealer run a scan of the system ans do an active test on the fan operation to determine what is wrong.

The AC runs the fan that cools the AC condenser and the radiator. You may have a problem with the cooling fan for the engine only or its control circuit, this fan is controlled by the main computer in the car called the PCM, you need the dealer to perform a test that operates the cooling fan and delivers back fault codes for any problems found with its operation.

YOUR ENGINE IS GETTING TOO HOT.THERMOSTAT BAD OR RADIATOR CORE CLOGGED AND FRONT GRILLE AIR FLOW BLOCK FROM DEBRIS OR THE COOLING FAN RELAY STUCK CLOSED POSITION MEANING BAD RELAY.

assuming the fuse is good and relays are good and the fan motor is good. the coolent temp sensor could be bad. go here to check it.

http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp;jsessionid=F212B754D81505B5695C832707CEF9C2.diyprod2-b2c12?chapterTitle=Coolant+Temperature+Sensor&partName=Engine+Cooling&pageId=0996b43f802e64b8&subChapterTitle=Testing&partId=0996b43f802e68d8

Before you get into this involved job I have a few suggestions. First is the pump leaking causing the system to lose coolant. Grab the fan and try to move it from side to side to see if there is play. Next when was the last time the thermostat was changed out. The thermostat can be stuck in a way as to restrict water flow. Another cause of over heating is a clogged radiator. Older cars can have a slug build up in the radiator core causing a significant cooling lose.
Water pumps on a Crown Vic is located on the front of the engine behind the fan. You should really get a service manual as there are a lot of steps in this job that must be done correctly to avoid future problems.
You start by draining the entire cooling system by opening up the drain plug on the bottom of the radiator. This antifreeze must be disposed of properly by taking it to a repair shop for pick up. Next remove the fan guard followed by disconnecting all the belts. Some people remove the radiator to gain working room. before removing the radiator disconnect the lower hose and the upper hose to the engine. The transmission oil cooling lines are next. Now remove all the bolts holding the radiator in place. As you can see this is not a job for a novas. If you are not mechanically inclined this could be a nightmare of a job.

No, the fan is supposed to come on only at certain temperatures.

Trace the wiring from the fan back, there should be a temp switch/relay in line. If there isn't,then someone has bypassed it and wired the fan to run when the car is running.