The fan runs constantly when the battery is inserted why?

The fans are getting a constant live feed so they can't turn off. Start by rechecking the wiring and the connectors for the fans and the sensor.

Check fan relay

Cooling fan module, will cause fan to run constantly or not at all. God-Bless!

Have you checked the ecm for trouble codes ? The fan runs all the time as a safety to try to prevent the engine from overheating.

try the relay. They usually do not fail in the on position.. but its a shot.

The most likely cause is due to the radiator fan constantly running and the engine not getting to operating temperature, thats why your temp gauge isnt going up, check all related wiring to the cooling fan and make sure there no bare wires that could be causing a short to ground causing the fan to constantly run, secondly check the fan relay, if all of that checks out check the coolant temperature sensor because the information from that sensor tells the computer when to turn the fan on and off, if the sensor is bad it could be telling the computer the engine is hot when in fact its not.

As long as you have the cells in the correct direction, the air flow direction you should be O.K. If you have a way of turning on a constant fan that will help dry them. I would shut the power button off to the electric air cleaner and run a constant fan for 24 hours. After that, turn the power on and the constant fan off. Turn up the heat and see if it works.

your fan rely is stuck...there are two of them and need replacement.  I believe they are in the fuse box.  You can tell which is bad by swapping them.   Good luck

Disconnect pos. battery cable for 3-5 minutes, then reconnect that should do it!!!!!!!!!!!!!

Fan is controlled by a temp sensor on Mobo and by CPU. I hard wired my "dead" fan to a constant 5V power supply (off the battery bus) and now it runs constantly, doesnt bother me and I have yet to lock up. My CPU cover actually discolored and warped because my fanless CPU got so hot!