THE PROBLEM IM HAVING IS THAT THE RADIATOR FAN ...

  • Tiny
  • gmarek
  • 1990 Nissan Maxima
  • 100,000 miles

The problem Im having is that the radiator fan won't kick on, but when I unplug the temp sensor it kicks on. I've gone ahead and changed the sensor to a new one but it still wont come on unless the sensor is unplugged.

Wednesday, December 5th, 2012 AT 12:23 AM

5 Answers

  • Tiny
  • KHLow2008
  • Expert
  • 41,976 posts

The fan would only come on when the required temperature turns the fan switch on. Is the engine overheating and is coolant level correct?

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Wednesday, December 5th, 2012 AT 2:30 PM
  • Tiny
  • gmarek
  • Member

Yes and yes, I also read elsewhere that the fan won't kick on if the car is idle? It would have to be actually running?

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Thursday, December 6th, 2012 AT 12:02 PM
  • Tiny
  • KHLow2008
  • Expert
  • 41,976 posts

The information you read about vehicle has to be running for the fans to work is wrong. In fact it is the reverse, up to a certain point. When vehicle is not moving, the coolant in radiator would heat up as well and this would require the fan to work to reduce the heat of the coolant.
When vehicle is moving, air flow is able to help cool the radiator resulting in less use of the cooling fans.
Do the fans come on when A/C is turned on?
When does the overheating occur?
Do you have coolant losses issues?
Is lower radiator hose very much cooler than the upper hose?

Radiator fans are controlled by the engine computer via signals from the Engine Coolant Sensor and if the fans are not coming on, it could be a faulty computer.

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Thursday, December 6th, 2012 AT 1:47 PM
  • Tiny
  • gmarek
  • Member

Oh alright. Figured that didn't sound right.
As for the fans going on when the A/C is turned on that would be a negative.
It hasn't overheated on me (yet)
After I did the radiator flush I drove the vehicle for about two hours my first stop was around 40 min mark of driving and the car did not overheat or anything then another 40 mins or so temp was not out of normal.
There is no coolant loss. As for the hoses they are both warm.
I went ahead and checked the thermostat and it seemed to be clogged as soon as I removed coolant and water was purged from the gasket.

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Friday, December 7th, 2012 AT 4:42 AM
  • Tiny
  • KHLow2008
  • Expert
  • 41,976 posts

When the coolant temperature is low, the thermostat would be closed and minimal amounyt of coolant can flow through.

From your description, I don't see any problem with the cooling system. During cold starts, it would take anywhere between 20 to 45 minutes for the fan to come on depending on weather conditions. Start engine and let it idle. As long as temperature does not go up, keep engine running until the fan comes on.

When the A/C compressor is running, the fans must be working otherwise you risk the A/C sytem building up excessive pressure and can rupture hoses if they are not in good condition.

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Friday, December 7th, 2012 AT 2:41 PM

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