coolant fans not turning very fast

Wife is out of town so I drive her van to work. In traffic, I look down at temp gauge and it seems to be running hotter than normal. Get it home, pull in the garage and pop the hood and let it idle. I'm watching the gauge, then I'm watching the fans. It goes past halfway up the gauge before any fan activity, then what fan activity I do get isn't very good. The fans were turning at what I would call 1/2 speed. When I turn on the a/c they seemed to kick it up and spin faster. Is there a sensor that has possibly gone out? Maybe the thermo deal that senses the radiator temp.

I know I will be changing head gaskets if I don't get it fixed before the wife gets back in it. She's not much of a gauge checker!!!!!

Any help would be appreciated.

Thanks
Wayne

Wayne,

There is a similar discussion going on in the Chevy Venture forum (about rising temp at idle).
http://www.automotiveforums.com/vbulletin/showthread.php?t=387829

Your van sounds like it is acting like mine. Is it "normal"? It is my opinion that it is.

As for the fans running at half speed - my GM manual says that is normal too (up to some 'unknown' temperature). The fans have both a "low-speed" and "hi-speed" operation mode, controlled by the PCM (computer).

When in low-speed mode, both fans are connected in "series" - effectively dividing 12 volts between the two (6 volts each).

In hi-speed mode, the fans are connected in "parallel" - each fan gets a full 12 volts.

This switching is done through 3 relays under the hood. Turning on the A/C enables hi-speed mode, to move more air through the condenser.

So you may NOT have a problem at all.

Hope this helps,

Hey Greg,
I really appriciate your help. We have had this van since it was new and this new temp condition is very out of the ordinary. I am guessing that the coolant temp switch may be going out, but it is running fine--fuel injection wise, usually when the CTS starts to act up the vehicle will start to run rich because the CTS is giving an untrue reading.

Do you know where this switch is located?

Thanks
Wayne

Just before the thermostat on the transmission end of the block. If you look right beneith the throttle body you will see a 3-wire connector that I think is color coded yellow.

Hey Greg,
I really appriciate your help. We have had this van since it was new and this new temp condition is very out of the ordinary. I am guessing that the coolant temp switch may be going out, but it is running fine--fuel injection wise, usually when the CTS starts to act up the vehicle will start to run rich because the CTS is giving an untrue reading.

Do you know where this switch is located?

Thanks
Wayne
Hey back,

I just got my van about 10 months ago, so I don't know if this "characteristic" is normal or not. I have noticed it all along.

As for a "coolant temperature switch", I don't think there is a separate switch.

My manual says that there is only an ECT (Engine Coolant Temperature) Sensor that sends data (a resistance value) to the PCM (computer) and the PCM turns the fans on and off at the appropriate times (and feeds the gauge on the dash).

Please let me know if you find something that changes this characteristic.

Take care,

I put some info up about when the engine cooling system fans should operate (from the manual). It might help (at least to understand how it SHOULD work).

http://www.links-to-golf.com/van/engine-cooling-system.html

Take care,