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Need to know what make model an year vehicle to say for sure . Most radiator fans are controlled by a relay . Do you know what a relay is ? The relay is energized by the engine computer / ECM/PCM . On the engine somewhere is a ECT - engine coolant temperature sensor , this tells the engine computer how hot the engine is . When the engines temp gets to around 201 degrees the computer turns on low speed cooling , then when it gets to around 221 degrees high speed kicks in ! Some vehicles have up too three relays controlling the fans .
turning of the ac switch will indicate if it is an ac problem for the fans.
some cars have the radiator fans running for up to 10 minutes after shut down . Run the fault codes to see if there is a faulty temperature sensor. how it works is this
the sensor is connected to the ecm and has power passing through. it When the sensor sensor a preset coolant temperature the power to the ECM is altered and so the ECM energizes the relays for the fans. If the fans are running continuously after shut down then the ECM still has the relays energized as it is still reading the requirement from the sensor.
Start the car and turn on the AC to max. Do either of the fans run with the AC compressor engaged? Also, there is a temp sensor for the fan circuit but I don't know exactly where it is located on that vehicle.
REPLACE THERMOSTAT AND RADIATOR PRESSURE CAP.MAKE SURE COOLANT NOT LOW.IF ALL IS GOOD CHECK FOR LEAKING WATER PUMP WEEP HOLE IF LEAKING REPLACE WATER PUMP.MAKE SURE COOLING FANS RUNNING.IF ENGINE RUNNING HOT WHILE SITTING LONG TRAFFIC LINE AND COOLANT NOT RUNNING.CHECK COOLANT FAN RELAYS AND FUSE.IF ALL IS GOOD HOT WIRE MAKE SURE COOLING FAN MOTOR GOOD IF COOLING FAN DONT RUN WHEN HOT WIRED FAN MOTOR BAD.IF FAN MOTOR OKAY AND FUSE RELAYS GOOD YOU HAVE FAULTY COOLING FAN WIRING.YOU COULD HAVE BAD ENGINE COOLANT SENSOR OR FAULT IN ECM CODE SCAN TO CHECK THEM BOTH.CHECK ENGINE OIL.LOOK LIKE MILK SHAKE YOU HAVE LEAKING HEAD GASKET.IF OIL LOOKS OKAY.YOUR ENGINE BLOCK, RADIATOR AND HEATER CORE NEED FLUSHING.
The ECM turns on the fans when the engine tempurature gets to around 210 degrees. You could have a bad coolant tempurature sensor, not telling the ECM that the engine is hot enough to turn on the fans. I would check to see if the fans come on when the A/C is turned on. Or there is a problem with the ECM. The ECM supplies a ground to the cooling fan relay to turn on the fans.
Check the coolant temperature sensor, it may have dirty contacts which is an easy job to fix. Signal from the coolant sensor indicates to the ECM that the engine is at running temperature and for the ECM to reduce the amount of fuel from the injectors (always a rich mix when warming up). (A little while later the thermostat should open allowing hot coolant to flow via the top hose to the radiator) The ECM rthen triggers the (5 pin) relay and the fans then come on. Check also the coolant relay fuse.
it is mounted under the radiator towards the drivers side,it is flat and held to the frame with 2 small bolts and has a flat wire connector,it doesnt look like a normal relay,its black with a silver plate on the front of it,hope this helps
the cooling fans are run by a relay it's located in the junction box. check this. there is also a thermoatic sensor located near the fans next to radiator. the fans should free spin when the engine is off this is a good indiacator that it's not the fan themselves. if the relay checks out(run engine and switch the fan relay with the a/c clutch relay when the engine reaches 180 degrees you will feel the upper radiator hose get hot the fans will turn on a short time later iof they don't it's the temp sensor near the radiator if they do it's a bad relay...please rate this thanks