Question about 2001 Mitsubishi Montero

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Location of the Auxiliary fan switch

I have a 2001 Mitsubishi Montero and the auxiliary fan will not come on so I am over heating. I believe it is the fan switch/thermostat that is the issue. I don't know where this is located. Can somebody tell me where this is located?

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The auxillary fan is used for AC cooling purposes, and your vehicle under normal circumstances should not overheat regardless of the status of the auxillary fan.

That being said, the auxillary fan is controlled by the PCM based on AC switch position via a fan control relay in your fuse box under the hood. There is no fan switch for it, as it is turned on based on PCM observance of AC control switch position.

Some things to look at regarding your overheat condition:

When the vehicle begins overheating, what are the conditions of the radiator hoses? Are both firm, or only one and the other soft? Are both hot, or is one hot and the other only warm?

Both a failed waterpump and a failed shut thermostat will show a hot hose on one side and only a warm hose on the other side of the radiator.

A failed (stuck shut) thermostat will also result in one very firm hose (highly pressurized and nowhere to go with the thermostat shut) and one relatively soft hose.

You can take the radiator cap off (BEFORE it pressurizes) and watch the water level as the car runs. If the thermostat is opening and waterpump is pumping, you will see fluid flow once it gets to operating temperature.

Watch your engine fan and see if it is engaged or just spinning freely. When warm and the engine shut off, the fan clutch should be engaged making the fan more resistant to turn. If it spins freely, the clutch is failing.

Check the area around the radiator and between it and the condenser for obstructions to airflow.

Obviously check the condition of the coolant for heavy scale/sludge. The 3.0/3.5 engines are notorious for turning coolant into thick rusty puddy.

Hope this helps!

Posted on Sep 11, 2009

  • eddieg619 May 14, 2011

    Hi, I have a similar problem my 3.5 sport overheats on really hot days specially on trips back from the mexican border. It can take from 15 o 45 minutes for the temperature to start slowly climbing. I've replaced the radiator, thermostat and fan clutch and still the same. The temperature goes back to normal as soon as I start driving. I will follow the advice on this post. Perhaps is time to take to an specialist. thanks


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Auxiliary fan

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