I have replaced the IAT sensor, checked all fuses and relays and hotwired the fan to make sure it works. The fan still doesn't come on. Is there another sensor or relay somewhere that I am not aware of?
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Re: Fan won't come on
RADIATOR FAN WORKS OFF OF THE COOLANT SENSOR NOT THE IAT SENSOR. CHECK YOUR RELAYS AND ALSO SEE IF IT COMES ON WITH THE A/C AS THIS OVERIDES THE COOLANT SENSOR FOR THE FAN. MOST LIKELY CAUSE WOULD BE A FAN RELAY
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This is normally the fan relay which is fried. It can be that the fan is pulling too much current , which causes the relay to fry. It is a good thing to change both fan and relay.
If the sensor is faulty, then you won t see coolant temperature on the instrument panel.
LOOK UNDER THE HOOD IN THE ENGINE COMPARTMENT. ON DRIVER SIDE FOR FUSE BOX.LOOK ON FUSE BOX COVER IT HAS LOCATION FOR FUSES AND RELAYS.MOST TIME PROBLEM WITH COOLING FAN CIRCUIT WILL CAUSE CHECK ENGINE LIGHT.BAD ENGINE COOLANT TEMPERATURE SENSOR WILL CAUSE COOLANT FANS NOT TO TURN CAUSE OVERHEATING. ON.REPLACE THERMOSTAT AND RADIATOR PRESSURE CAP SEE IF STOP OVER HEATING. IF ALL LOOKS GOOD HOTWIRE COOLANT FANS MAKE SURE FAN MOTORS ARE GOOD AND NO SHORTS AT FAN CONNECTOR WIRES.
IF CAR OVERHEATING AT STANDSTILL OR IDLING IN A LONG TRAFFIC LINE.COOLANT FAN NOT TURNING ON.MORE LIKELY COOLANT TEMPERATURE SENSOR NOT WORKING.USE A SCANNER TO CHECK COOLANT TEMPERATURE WHEN ENGINE HOT.IF TEMPERATURE READ LOW COOLANT TEMP.SENSOR BAD.IF SENSOR OKAY.CHECK COOLANT FAN FUSE AND RELAY.ALSO HOTWIRE FAN TO SEE IF FAN MOTOR WORKING.IF NO REPLACE FAN MOTOR.IF FAN MOTOR GOOD FUSE AND RELAY COOLANT FAN MOTOR WIRE CONNECTOR IS DAMAGED OR HAS BROKEN WIRE.
first check the fuse, usually in the fusebox under the hood. Then, with the engine hot and running, pull out the fan relay (usually in the same box as the fuse). If it's working, it should click when removed and again when replaced in its socket. If it doesn't, suspect the relay or sensor has failed. If your gage runs off the same sensor and works, it's probably fine. If you're good with electronics, you can also test the sensor. If these are all good, either the wire to the fan is bad or the fan itself is bad. You can test the wire for voltage with a test light hooked to the fan connector, and you can test the fan by hotwiring it to the battery.
WHEN CAR STARTING OVERHEATING MAKE SURE COOLANT LEVEL DIDNT GET TOO LOW. IF NOT I WOULD REPLACE THERMOSTAT AND RADIATOR PRESSURE CAP IF OVERHEATING WHILE SITTING IDLING COOLING FAN NOT COMING ON.CHECK COOLING FAN FUSE AND RELAY IF ALL IS GOOD.CHECK COOLING BY HOTWIRING IT.IF RUNS YOU HAVE A BAD COOLANT TEMPERATURE SENSOR OR FAULT IN WIRE CIRCUIT.IF FAN DONT RUN WHEN HOTWIRED REPLACE FAN MOTOR.IF CAR STILL KEEP OVERHEATING CHECK ENGINE OIL LOOKS LIKE MILK BLOWN HEAD GASKET.IF OIL LOOKS OKAY YOU NEED RADIATOR AND ENGINE FLUSHED OUT.
REPLACE THERMOSTAT AND RADIATOR PRESSURE CAP.IF STILL OVERHEATING CHECK TO SEE COOLANT COMING ON IF NOT CHECK COOLANT FAN FUSE AND RELAY.IF BOTH GOOD.HOTWIRE COOLANT FAN TO SEE IF IT WORKS IF NO REPLACE FAN MOTOR.IF FAN MOTOR RUNS FAN MOTOR WIRE HAS SHORT OR COOLANT TEMPERATURE SENSOR FAULTY.
DO A QUICK TEST CHECK.HOTWIRE FAN TO SEE IF IT COME ON.IF NO FAN MOTOR NEED REPLACING.IF YES FAN MOTOR RUN.CHECK FAN FUSE AND RELAY.IF BOTH IS GOOD YOUR COOLANT TEMPERATURE SENSOR IS OPEN MEANING ITS BAD.
yes the head gaskets leaking on modern aluminum head engines is all to common. never overheat them, if they start to get hot shut it down and find out why, it can of course be the fans and plugged radiators or faulty thermostats but sounds like in your case the head gasket is leaking and combustion gas is entering the cooling system and this causes an overheat
FIRST SCAN CAR TO SEE IF COOLANT TEMPERATURE SENSOR IS WORKING SEE IF YOU GETTING ECTS CODES. IF NOT CHECK THE COOLING FAN FUSE AND RELAY.IF BOTH GOOD HOTWIRE THE COOLING FAN USING JUMPER WIRES TO CAR BATTERY.IF FAN DONT WORK REPLACE THE COOLING FAN MOTOR ITS FAULTY.