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Re: 91 Legend cooling fan turns on by itself
Good place to start is the temp. sending unit that turns the fan on and off, usually located in or near the bottom of the radiator. On many cars, the is is how the system works, but only until the engine cools down, and it should never run the battery down. I suspect the temperature sending unit is shorting out.
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RADIATOR COOLING FAN NOT RUNNING COULD BE BAD ENGINE.COOLANT TEMPERATURE SENSOR IS FAULTY IF COOLING FAN IS NOT TURNING ON AT SET TEMPERATURE OF 196 TO 203 DEGRESS.CHECK SEE COOLING FAN RUNNING WHEN ENGINE RUNNING HOT.IF YES FLUSH RADIATOR , FLUSH ENGINE BLOCK, HEATER CORE,REPLACE RADIATOR CAP.MAKE SURE YOU HAVE 50/50 ANTIFREEZE AND WATER IN THE COOLANT SYSTEM.CHECK WATER PUMP WEEP HOLE IF LEAKING REPLACE WATER PUMP. IF COOLANT FAN DONT TURN ON 196 TO 203 DEGREES, YOU HAVE FAULTY COOLING FAN,SHORT IN FAN WIRING OR ENGINE COOLANT TEMPERATURE SENSOR FAULTY.IGNITION TIMING WILL CAUSE ENGINE TO OVER HEAT.
SOUND LIKE ENGINE OVERHEATING,CHECK COOLANT LEVEL MAKE SURE YOUR RADIATOR FULL OF ANTIFREEZE.IF YOUR COOLANT OVERFLOW JUG IS EMPTY COOLANT LEVEL IS LOW.NEED ADD MORE COOLANT TO OVERFLOW UNTIL COOLANT STAY AT FULL COLD MARK. DONT OVER FILL COOLANT OVER FLOW JUG.IF COOLANT OKAY ENGINE OVERHEATING REPLACE THERMOSTAT.MAKE SURE ENGINE COOLING FAN IS WORKING IF YOU COME TO A STOP CAR SITS FOR A LITTLE WHILE START OVERHEATING THE COOLING FAN NOT TURNING ON , BECAUSE COOLANT FAN FUSE BLOWED OR YOU HAVE BAD RELAY,THE ENGINE COOLANT TEMPERATURE SENSOR FAULTY.IF YOU HAVE THE CLUTCH TYPE COOLING FAN, MAKE SURE WHEN TURNING CLUTCH FAN WITH HAND COOLING FAN SHOULD HAVE RESISTANCE WHEN HOT.IF CLUTCH FAN FEEL WOBBLY AND LOOSE REPLACE IT.TAKE VECHICLE TO AUTO ZONE OR ADVANCE AUTO PARTS OR ANY AUTO PARTS STORES THEY WILL CODE SCAN CAR FREE AND GIVE YOU THE CHECK ENGINE LIGHT TROUBLE CODE TO SEE WHAT CAUSING CHECK ENGINE LIGHT TO TURN ON.
Many cars have this feature. The fan will run for a few minutes at a time until the coolant in the radiator drops below a certain temperature. Most vehicles with this feature will have a warning label on the radiator shroud indicating that the fan may start without warning when the engine or radiator is still hot. The only time you would need to be concerned would be if the fan continues to run without turning itself off, and causing the battery to be drained.
The engine fan circuit is separate from the ignition system and it is perfectly normal for the fan to sometimes be off while the engine is on and sometimes on while the engine is off. It should turn itself off independently. If it runs 24 hours a day without starting the engine then the relay or water temperature sensor will need replacing.
If While A/C is on Fan does not come on I would Check Fan By unplugging it first than apply Pos+ and Neg- to it if it comes on that's eliminated Then go to step 1-3 one of them is bad I usually replace Engine temp sensorsno mater what they are Crucial components for the safety of the Engine.
the sensor is located at the rear side of cylinder head between transmission and engine under the thermostat hosing but make sure to have some one aply direct power to fan to se if fan still goos if not replace it, and the sensor all what you have to do to test it start the car unplug the sensor and if the fan come on then replace the sensor i will recomend to replace thermostat also and make sure is full of coolant