when does the cooling fans kick in


armagh1
07-21-2009, 08:43 PM
I have a 2001 silhouette, I had an issue that the temp gauge would go 3/4 way up when idle, i noticed the cooling fans didnot come on, i turned the ac on full and the fans worked I have bled the cooling system, replaced the coolant temp sensor and still the fans do not run unless the ac at full blast. when should the fans kick in with temp needle 1/2 way less or more

Thanks

for responses

roadrunner2
07-22-2009, 11:05 AM
I have a 2001 silhouette, I had an issue that the temp gauge would go 3/4 way up when idle, i noticed the cooling fans didnot come on, i turned the ac on full and the fans worked I have bled the cooling system, replaced the coolant temp sensor and still the fans do not run unless the ac at full blast. when should the fans kick in with temp needle 1/2 way less or more

Thanks

for responses

I had a similar problem with a 2000 Silo.

The temp gauge would read way below the half way mark when at operating temp and when idling in traffic would creep up to well over the 3/4 mark and still the fans wouldn't turn on.

Like you did, I turned on the A/C to run the cooling fans and the temp immediately dropped back to normal.

I suspected there was a wrong T-stat installed and it turned out I was right (for once).

To me it seemed the engine ran too cool, so I changed the T-stat from the 180 that was in the engine to the 195 it was supposed to have.

Now the temp gauge reads (at operating temp) just a bit above the 1/2 way mark and doesn't overheat when idling.

As far as the cooling fans kicking in according to temp, I found mine was heating up to almost the red line (240+ deg) before activating.

rockwood84
07-30-2009, 11:48 PM
the 1st fan will kick in a little above 1/2 and if still climbs the 2nd fan will kick in at 3/4 to try and cool it down.with the a/c on both fans kick in a little above 1/2

depalma
04-21-2010, 09:23 AM
the 1st fan will kick in a little above 1/2 and if still climbs the 2nd fan will kick in at 3/4 to try and cool it down.with the a/c on both fans kick in a little above 1/2

I have a 1999 and a 2003 Silhoutte and typically they both show a normal temp gauge reading at the 1/4 mark on the gage.
After some recent coolant work on the 1999, the temp gauge will now go up above the 1/2 mark at which point both fans will kick in.The temp will then go back down to the 1/4 level. After that I now noticed more varablity in the temp needle position.
All of the above is with the AC off. Coolant levels in overflow tank is fine.
no coolant level loss noted. Oil looks OK also. Engine perorms perfectly.
and yes the low coolant level is always on even though the sensor was replaced. I have learned that this false reading is due to residual contamination from the failed intake manifold gasket that was replaced.
My questions are:
Should one fan come on first ? before the second fan is called for?
What sensor causes the fan to come on? and where is it located?
Should I be concerned about the temporary high temp readings.
Any other suggestion would be appreciated.

Airjer_
04-21-2010, 10:05 AM
Should one fan come on first ? before the second fan is called for? Yes, there is a low speed and a high speed.

What sensor causes the fan to come on? and where is it located? The fans are controlled by the PCM. The low fan should come on about 220 degrees. The high and low fans can be commended on and off with a scan tool.

If you pull the "cool fan 1" relay with the key on there should be voltage at two pins, ground at one pin, and one pin with neither. With a test light hooked to power probe that pin and start the vehicle. When the temp hits around 220 the test light should illuminate. If it does than try swapping the relay. If it doesn't that you have wiring or PCM issues.


Should I be concerned about the temporary high temp readings.
Any other suggestion would be appreciated.[/quote]
Only if the actual temp is more than roughly 230 degrees. The other possibility is your gauge is reading high. Again this can be confirmed with scan tool data. If the gauge says 3/4 and the coolant temp data says 220 than there is a gauge issue.

armagh1
04-21-2010, 02:58 PM
is the cool fan 1 relay in the fuse box in by the engine where on the temp gaguge is 220 degrees

Airjer_
04-21-2010, 10:47 PM
Typically 195 to 200 is about center. 234 (roughly) is just starting to touch the red zone.

LMP
04-23-2010, 07:09 AM
http://www.my-chevy-venture.com/temperature-gauge.html
BTW, browse through www.my-chevy-venture.com and see very detailed and well orchestrated info.
kudos to that forum member.

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