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Discussion Starter · #1 ·
Trying to troubleshoot when my fans should be on...
Can someone with a 3.5L tell me if the cooling fans run:

With the key on, engine off (cold engine)?
After starting (cold engine)?
With the A/C selected?

Thanks.
 

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for 2 fans :

one fan comes on at low temps right when the tstat opens up
the second fan is used for a/c and defrost operation.
the second fan also comes on if the low speed fan can not keep up with things on its own tempature wise
 

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Discussion Starter · #3 ·
So what your saying is there is no fan running initially, but soon after the engine starts to warm up one fan comes on? Does the A/C selection turn on a fan when the engine is cold?
 

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the fan only comes on at lower temps if the a/c or defrost is on
 

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A/C or defrost will turn the fan on right qafter starting it with a cold engine. Also, IIRC, the fans will turn on shortly to check operation of them after initial start up for like a couple seconds.
 

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Trying to troubleshoot when my fans should be on...
Can someone with a 3.5L tell me if the cooling fans run:

With the key on, engine off (cold engine)?
After starting (cold engine)?
With the A/C selected?

Thanks.
Yes, the fans(both) should be on LOW with the A/C on and the engine running.

for 2 fans :

one fan comes on at low temps right when the tstat opens up
the second fan is used for a/c and defrost operation.
the second fan also comes on if the low speed fan can not keep up with things on its own tempature wise
Unless the wiring is different between the V6's and V8's, BOTH fans operate together. On LOW speed, both fans are electrically connected in series and therefore run at half of system voltage. On HIGH speed, they are connected in parallel and run at full system voltage. When the A/C system is active, the fans run on LOW to keep the condensor coil cooled down unless the engine temperature is high or the A/C system is heavily loaded.
 

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Discussion Starter · #8 ·
Ok, that is helpful for the A/C side of things, but I really need to know if the fans come on when the engine is first started with a cold engine. My fans do not and I'm afraid to run the temperature up too far to see if they come on at higher temps. I've run the temp up to one third of the gage between cold and hot and they do not run. I have no DTC codes and I've done the diagnostic check for a fan code and everything checks good. My FCM on the front relay/fuse box is not signaling the main fan relay to close. That is my current obstacle...what causes the FCM to send the signal? Is it the coolant sensor or PCM or?
 

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If the A/C is not on, the fans will not come on until the engine temp gets to about 215-217F. The low speed mode will activate and cool the engine by 5 degrees and the fans will turn off. Do you have the EVIC option since it will show actual engine temperature? Just drive the car and watch the temp gauge if you don't have EVIC. The fans will come on right around the halfway mark on the gauge.
 

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Yes, the fans(both) should be on LOW with the A/C on and the engine running.


Unless the wiring is different between the V6's and V8's, BOTH fans operate together. On LOW speed, both fans are electrically connected in series and therefore run at half of system voltage. On HIGH speed, they are connected in parallel and run at full system voltage. When the A/C system is active, the fans run on LOW to keep the condensor coil cooled down unless the engine temperature is high or the A/C system is heavily loaded.
ya that could be. i didnt have time to look up the schematic for this thread but i went on general knowledge of how most 2 fan systems work
 
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