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Thread: Fan temp behavior

  1. #1

    Fan temp behavior

    2004 Impala SS - SC 3.8l engine.

    I'm running a 180 degree thermostat and have the fans setup as in the photo. (Sorry for quality)

    But I occasionally notice in traffic, etc the temps climb upwards for 212-215ish. Yesterday I managed to pull over when they were at 214 and neither fan was on. (AC off). Turning the AC on does make the fans turn on.

    Is there some wonkyness with the settings in here?



  2. #2
    Tuning Addict 5FDP's Avatar
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    I lean towards a possible faulty temp sensor if they do not come on with your settings.


    And I'd inspect your cooling system. I'm not saying is faulty and I know this may not mean much but when I owned my grand prix the temps rarely would rise to those temps even in traffic. I maybe saw 205ish at time but even without the fans running it was able to cool down on it's own. Never hurts to blast out the radiator fins from behind and make sure the air duct/deflector under the rad is doing it's work correctly to bring in fresh air. I also only ran a 195 thermostat as there is no advantage to running the motor 10 degrees cooler on the open road.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
    Quote Originally Posted by 5FDP View Post
    I lean towards a possible faulty temp sensor if they do not come on with your settings.

    Is there another temp sensor for the fans besides the one in the front head that I'm getting my readings from? (FWIW mine is only a 2 wire unit)

    As long as I'm moving or have the climate control calling for AC the temp stays in the 188-192 range.

    I just noticed in the driveway while watching the scanner that the fans came on low speed at 206 or so, and high speed around 214. At 211 they kicked back into low.

    [edit] Just found some old posts discussing similar issues on the 3800 platform. It seems the solution is to set CC override to disabled. I'll try this tomorrow and report back.

    [edit #2]
    Indeed setting CC override to disabled makes the fan behave as programmed. With this set to enabled the climate control takes care of the fans, but must have factory fan temps set in the module somewhere.

    So in summary. On this platform to change fan settings CC Override must be disabled.
    Last edited by scoob8000; 08-23-2015 at 05:15 PM.