Cooling fan will not turn off.

  1. Welcome to VW Passat Forums : Volkswagen Passat Forum – General discussion forum for Volkswagen Passat

    Welcome to VW Passat Forums : Volkswagen Passat Forum - a website dedicated to all things Volkswagen Passat.

    You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, Join VW Passat Forums : Volkswagen Passat Forum today!
     
Results 1 to 12 of 12
Like Tree13Likes
  • 2 Post By Emry
  • 2 Post By VAGguy
  • 2 Post By ylwagon
  • 2 Post By FrescoGreen01.5
  • 4 Post By FrescoGreen01.5
  • 1 Post By VAGguy

Thread: Cooling fan will not turn off.

  1. #1
    Neutral
    Join Date
    Apr 2017
    Location
    Colorado
    Posts
    12

    Cooling fan will not turn off.

    2003 Passat 1.8t Wagon, GLS AWM engine code.
    I bought this vehicle while living in the mountains, now I am in a wrm climate, have found a connection under the hood by the power steering pump area, when I connect the connectors my electric cooling fan comes on and will stay on until the battery is dead, no matter what the temp is. I am having to plug it in when driving so my car will not overheat when sitting in traffic or at a stop, then unplug the connectors when I stop driving. Anyone have an idea of what is going on? Thank you.

  2. Remove Advertisements
    VW Passat Forum
    Advertisements
     

  3. #2
    3rd Gear axenstar's Avatar
    Join Date
    Mar 2011
    Location
    CharlestonSC/Atlanta
    Posts
    1,697

    Cooling fan will not turn off.

    I had the same issue with my 98 GLS. I pulled a relay from the cluster under the steering column. ( I don’t remember which one.)
    It stopped running constantly and now kicks in when the ac is on.


    Sent from my iPhone using Tapatalk

  4. #3
    3rd Gear
    Join Date
    Sep 2015
    Location
    Raleigh, NC
    Age
    48
    Posts
    1,807
    Following as mine will randomly start and stop all the time no matter cold or hot.

  5. Remove Advertisements
    VW Passat Forum
    Advertisements
     

  6. #4
    in dire need of an organic chemistry lesson
    Join Date
    Jul 2007
    Location
    Michigan
    Age
    56
    Posts
    2,163
    Quote Originally Posted by jjpark View Post
    Following as mine will randomly start and stop all the time no matter cold or hot.
    The random behavior of the fan is normal. It starts when the temp gets to a predefined in the ECM. But if the fan runs constantly I think the relay has closed and stuck. Changing the relay should resolve the issue. At its minimum it should be tested for proper functioning.
    cchief22 and jjpark like this.

  7. #5
    Motel Room Moderator VAGguy's Avatar
    Join Date
    May 2006
    Location
    Abingdon, MD
    Age
    42
    Posts
    23,180
    Quote Originally Posted by jjpark View Post
    Following as mine will randomly start and stop all the time no matter cold or hot.
    If the A/C is not switched on, then the signal to turn on the aux fan should be coming from the thermal fan switch in the bottom radiator hose connection. Cheap and easy to replace as troubleshooting. Note, this is NOT the one at the back of the head which is a green sensor.
    https://www.fcpeuro.com/products/aud...481bmy#fitment
    axenstar and jjpark like this.
    Glutton for Punishment: 16 A4 S-line Sport pkg Prem+, 04 Passat 1.8T GLS Variant Manual swapped, 2017 Q5 Prem+

  8. #6
    3rd Gear axenstar's Avatar
    Join Date
    Mar 2011
    Location
    CharlestonSC/Atlanta
    Posts
    1,697
    Quote Originally Posted by VAGguy View Post
    If the A/C is not switched on, then the signal to turn on the aux fan should be coming from the thermal fan switch in the bottom radiator hose connection. Cheap and easy to replace as troubleshooting. Note, this is NOT the one at the back of the head which is a green sensor.
    https://www.fcpeuro.com/products/aud...481bmy#fitment
    Good catch.


    Sent from my iPhone using Tapatalk

  9. #7
    5th Gear
    Join Date
    Sep 2002
    Location
    Fallbrook CA USA
    Posts
    5,147
    Quote Originally Posted by VAGguy View Post
    If the A/C is not switched on, then the signal to turn on the aux fan should be coming from the thermal fan switch in the bottom radiator hose connection.
    Correct, and the clue is that the fan runs when the (faulty) radiator temp switch is plugged in. To the OP: I wouldn't waste time plugging/unplugging that thing, because the only time it would switch on the fan is if the mechanical fan wasn't working, or a high-load and low speed situation was occurring. Watch your temperature indicator, and if it points at the middle of the range, it's not overheating.
    VAGguy and jjpark like this.

  10. #8
    3rd Gear
    Join Date
    Aug 2011
    Location
    Westerville, Ohio
    Posts
    1,037
    I concur with post #5, faulty thermal fan switch, if that's what the OP is unplugging.

    Correct operation of the electric fan is as follows:

    The fan has two speeds, low and high. Low is powered via a resistor, high directly from battery voltage (via a fuse).

    With A/C off and engine at normal temperatures or cold, fan is off. The fan can be called for by either the A/C or the coolant temperature.

    When the A/C is switched on, the fan runs in low speed.
    If the A/C refrigerant high pressure switch closes, the fan runs in high speed.

    The engine coolant temperature switch is located at the radiator bottom connection, just behind the fans. (Not to be confused with the coolant temperature sensor, an analog sensor back near the firewall.) The switch has two separate contacts which close at different temperatures.

    When the first speed contact closes, 197 to 206°F, the fan runs at low speed.
    When the high speed contact closes, 210 to 221°F, the fan runs at high speed.

    (The fan runs at the highest speed demanded by either the A/C or coolant temperature switch.)

    The above activate the low and high speed fan relays under the dash, which switch power to the fan motor. In the V6, the relays are integrated in a fan control module under the hood; it also controls the afterrun coolant pump (not present in the 1.8T).
    axenstar and jjpark like this.

  11. #9
    3rd Gear
    Join Date
    Sep 2015
    Location
    Raleigh, NC
    Age
    48
    Posts
    1,807
    Thank you for the replies. I will go a head and change out the sensor at the radiator and see what happens. Will I need to bleed the cooling system after this? The part that Vagguy linked me too doesn't appear to have any O ring so I am guessing I won't but want to double check....

    If the sensor doesn't fix the issue. I will move on to the relay.

    Thank you

  12. #10
    3rd Gear
    Join Date
    Aug 2011
    Location
    Westerville, Ohio
    Posts
    1,037
    jjpark, you could simply unplug the coolant thermal switch at the radiator for troubleshooting--just watch your temperature gauge. Except in really hot weather with stop & go traffic, the mechanical fan is plenty adequate (presuming the viscous clutch is in good condition).

    Another item worth mentioning: for some time, one of the third-party parts lookup systems had the wrong part identified for the coolant thermal switch. They would sell you a temperature sensor instead... not good.

    Both the coolant thermal switch and coolant temperature sensor will fit in either location and will plug in. But they are electrically completely different:

    > Coolant thermal switch, lower radiator pipe: contains two switches, normally open, close on high temperature (see Post #8)

    > Coolant temperature sensor, rear of engine near firewall: contains two thermistors which vary in resistance with temperature. One thermistor is wired to the ECM, the other to the temperature gauge. They measure 1.5-2.0 kOhm at 30°C, 275-375 Ohms at 80°C (see Bentley G24-5 for graphs).

    So, if a previous owner installed a temperature sensor instead of a thermal switch, your fan might operate strangely. You could verify this with an ohmmeter on the Coolant thermal switch. It should measure open circuit unless the engine is hot, nearly zero ohms if it is.
    axenstar, jjpark, VAGguy and 1 others like this.

  13. #11
    Motel Room Moderator VAGguy's Avatar
    Join Date
    May 2006
    Location
    Abingdon, MD
    Age
    42
    Posts
    23,180
    I wonder if Gypsy fixed their issue....and jjpark too.
    jjpark likes this.
    Glutton for Punishment: 16 A4 S-line Sport pkg Prem+, 04 Passat 1.8T GLS Variant Manual swapped, 2017 Q5 Prem+

  14. #12
    3rd Gear
    Join Date
    Sep 2015
    Location
    Raleigh, NC
    Age
    48
    Posts
    1,807
    Quote Originally Posted by VAGguy View Post
    I wonder if Gypsy fixed their issue....and jjpark too.
    I have not Life got in the way and now it's been super hot recently so I haven't really though about it. I do think my main fans clutch is on it's way out as I think it is one of the chirping noises I have had for some time.

  15. Remove Advertisements
    VW Passat Forum
    Advertisements
     

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Where do you live?

Year of model

car model

Please select your insurance company (Optional)

Log-in

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

    Similar Threads

    1. Cooling fan won't shut off (and other electrical issues...) HELP!!!
      By Toxic Dover in forum Volkswagen Passat B6 Discussion
      Replies: 10
      Last Post: 10-19-2018, 01:03 AM
    2. Replies: 2
      Last Post: 02-12-2013, 07:55 PM
    3. Replies: 3
      Last Post: 02-12-2013, 02:19 PM
    4. Cooling Fan/Cooling Fan Module
      By zmetel in forum B6 Garage
      Replies: 5
      Last Post: 07-29-2010, 07:43 AM
    5. Electric Fan will not turn off
      By CossieCos in forum Volkswagen Passat B5 Discussion
      Replies: 3
      Last Post: 08-05-2006, 05:47 AM

    Tags for this Thread

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •  
    Powered by vBadvanced CMPS v4.1.2