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What temperature does your fan kick in?

Discussion in 'A3/S3 Forum (8L Chassis)' started by metricspaces, Nov 13, 2011.

  1. metricspaces
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    metricspaces Member

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    [Nov 13, 2011]
    Hi, could someone check what temperature the fan kicks in on the S3? In particular if you have a pre-facelift (just in case there is any difference between pre & post facelift!).

    You can check the temperature by using channel 49 on the air conditioning console. Just get the engine warm. Park it up and wait for the temperature to rise, pop the bonnet and see what temperature the fan comes on at.

    This thread here has some info from ELSAWIN on the temperature that the fan should kick in at http://www.audi-sport.net/vb/air-conditioning/107293-8l-s3-air-con-fan-not-working-help.html

    My fan was only kicking in at 104C and apparently the signal was going to the fan to kick in at Stage 1 but it the fan wasn't starting. So it seemed my fan was gone.

    I replaced the fan. Now the fan kicks in at 99C and cuts out at 98C.

    I was expecting my fan to kick in somewhere between 92 - 97C.

    This seems quite odd. The fan doesn't control what temperature to kick in at from what I have read. That is controlled by the fan control module. So simply replacing the fan should not have any affect on what tempature it kicks in it? But it has in my case. Previously on the old fan it kicked in at 104C, whilst now it kicks in at 99C.

    Why has the temperature that my fan kicks in at gone from 104C down to 99C by simply changing the fan?

    Does it sound like my fan was never broken? Because it is still not kicking in at Stage 1.
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  3. metricspaces
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    metricspaces Member

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    [Nov 13, 2011]
    Any ideas on this one?
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  4. colicabcadam
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    colicabcadam Guest

    [Nov 13, 2011]
    my temp reaches around 104c on the central dash when you use the digital sensor board before it drops back down to around 98, the dash on the clcoks will always stay at 90 unless the temp rises above 110

    remember that the temp is coming from the engine block, so the temp on the rad will be lower, so if you are reading 99before it comes on i wouldnt worry at all
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  5. metricspaces
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    metricspaces Member

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    [Nov 13, 2011]
    colicabcadam, sounds like yours is working similar to mine. But possibly your fan is just not kicking in at stage 1 speed, but instead at stage 2 speed.

    When ELSAWIN says stage 1 should cause the fan to come when the temperature is in the range 92C to 97 C, what sensor is this temperature meant to come from?

    I read that the coolant temp that causes the fans to kick in is precisely that temperature that you see on channel 49 on the air conditioning console.

    Can anyone confirm if my understanding of this is true? Because if it is, then stage 1 speed of my fan should kick in when channel 49 on the air conditioning console is in the 92-97c range.
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  6. metricspaces
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    metricspaces Member

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    [Nov 13, 2011]
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  7. colicabcadam
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    colicabcadam Guest

    [Nov 14, 2011]
    my s3 was fine, stage 2 very rarley comes on and there's pretty much no chance of it coming on in winter

    you can hear the difference, stages 2 is LOUD

    the radiator fan switch located at the bottom of the rad is what controls the fans, it sends a signal to the fan control module, which then turns on the fan, remeber the fan control module also turns them on if the air con is on

    the rad switch will 100% be a different temp to that shown on the 49 option as that options gets info from the temp sensor in the block
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  8. colicabcadam
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    colicabcadam Guest

    [Nov 14, 2011]
    oh and if it really bothers you, whack some cardboard on the rad, the high speed will come on when 49 reaches around 106/108, which would be aaround 100 at the rad

    mine too kicks in at around 99 on 49

    there's nothing wrong
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  9. metricspaces
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    metricspaces Member

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    [Nov 14, 2011]
    Thanks, that makes sense as to why looking at channel 49 on the climate control is not the correct thing to be looking at if I want to see if my fans are starting within the temperature range specified by ELSAWIN i.e. Stage 1 on: 92 ... 97 °C/ off: 84 ... 91 °C

    Can you monitor the temperature that the radiator thermo switch is reading using VAG-COM?
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  10. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Nov 14, 2011]
    no, the rad switch is just that, a switch. Ie its not a sensor, and its not used for anything other than switching the relay in the fan controller.

    The switch also sits in the radiator bottom hose, ie the return to the engine, AFTER the waters been cooled by the rad. The Sensor your looking at on channel 49 is mounted in the cylinder head on the feed TO the rad. So a higher reading on 49 is to be expected.

    In traffic my temp reading on 49 climbs to around 98 then floats around there usually between 97 and 99, presumably as the fan comes on and off.
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  11. colicabcadam
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    colicabcadam Guest

    [Nov 14, 2011]
    no you cant, the rad switch is a simple on / off when a certain temp is reached - it is fair to say there will be a difference of around 7 degrees between the rad switch and the engine block

    i would not panic too much, your car is acting very normal, almost every engine both car and bike will not have an electrical fan kick in until the temp in the block reaches around 100 - 104
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  12. metricspaces
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    metricspaces Member

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    [Nov 14, 2011]
    Thanks guys. Sounds like I am safe so.
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  13. metricspaces
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    metricspaces Member

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    [Nov 14, 2011]
    Seems I spoke too soon! My fan was kicking in when channel 49 in the climate control reached 99c.

    But this evening after driving for about 40min and parking up, I left the engine running to see what would happen.

    The temperature rose to 110C on channel 49. The fans never kicked in!

    Then I turned the engine off and the fans kicked in at stage 2 speed (much louder and faster than stage 1 speed).

    I've replaced the coolant temp sensor and the fan. Anyone got an idea of what could be wrong?

    Could it be the radiator thermo switch? Or the fan control module?
    #12

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