mikee30

Hi,
I have a 2005 Uplander with 60,000KM that has started the following issue...
As soon as I start the car, I hear the fan engage and the temperature gauge stays on cold. Even after driving the truck around, the temperature gauge does not move at all and the fan remains on. However, my heaters work perfectly and even if the gauge reads COLD, I have perfect heating in the car.

I thought this might have been a sign of a thermostat stuck open, however, the radiator fan remaining on makes me think there is a sensor involved that I am not familiar with. Where should I start in diagnosing the problem?

Thanks!

U.Nanimous

Normally if the sensor was reading too hot the fan would come on and the gauge would read high. This sounds like you could have two separate issues with the same system unless...if the computer senses a fault with the sensor it turns the fan on but doesn't show a temp on the gauge because of the fault. Have you hooked up a scanner to see if anything is going on in the computer? If you want to check out the sensor, it may be next to or below the thermostat.

Otherwise you need to look at reasons the fan would turn on besides high coolant temp. Is the A/C on? Not sure if it is supposed to when you select defrost which is more likely appropriate for this time of year. But that still leaves the reading which is likely either the sensor or the gauge.

cleveland63b

its probably ECT sensor related, the system would default to having the fan run constantly and if your heater is working like normal its probably not the thermostat. I'm a little surprised theres no check engine light

U.Nanimous

Exactly!