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    Thread: When does radiator fan turn on?

    1. 04-20-2006 11:44 PM #1
      I'm not sure if I have a bad coolant temperature sensor. When is the fan supposed to turn off? Is it on any time the engine is running? My fan works fine when jumping the terminals but want to determine if the coolant temperature sensore needs replacing. Any insight would be appreciated. Thanks.

    2. Member BumblebVR6's Avatar
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      04-21-2006 12:43 AM #2
      Could be the fan module or the fan switch in the radiator. Does the A/C work in the car? If it does, does the fan turn on when you turn the A/C on?

    3. 04-21-2006 11:36 AM #3
      The A/C doesnt work, and thats a whole other can of worms. That was my first DIY project, and man, what a PITA it turned out to be. I'm going to check the radiator switch this afternoon, but I know for sure that the fans themselves are good. What I'm not sure of is if the switch is bad. I guess to know this I need to figure out if the fans arent coming on when they should be. I havent heard the fans in about a month, even after shutdown after highway driving. Is there any way to test the radiator switch itself?

    4. Member BumblebVR6's Avatar
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      04-21-2006 01:36 PM #4
      You can jump the pins in the fan switch connector to see if the switch itself is bad. So you put power directly to the fan and it worked?

    5. 04-21-2006 03:09 PM #5
      I got power to the fans by jumping two contacts on the coolant temperature sensor, which is a 4-pin yellow connector located on the passenger side of the thermostat housing. I'm gonna test the rad fan switch this afternoon and see what happens. Can I assume that if the fans start up the switch is the root of the cause? I havent had any overheating yet, but its getting hotter outside and dont want to push my luck. Do you know when the fan is supposed to come on? Should it be operating any time that the engines running or does the coolant need to reach a certain temperature?

    6. 04-21-2006 08:12 PM #6
      Fan also works when I jumper the radiator fan switch. No all I need to know is how to determine whether the switch is bad (i.e. when should the fan be operating, and does mine function properly)

    7. 04-22-2006 02:30 AM #7
      im also working on my fans. i read in bentley that to test the fan switch, you take the 3 pin connector ( 1 power and the 2 fan speeds) and jump power to one of the speeds. my fans would turn oin when i jumped power to the first speed but did nothing when i jumped power to the 3rd pin. im going to pick up a new switch regardless its getting hot out

    8. Member BumblebVR6's Avatar
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      04-23-2006 01:44 PM #8
      It gets hot in CT and ON? LOL!! You guys need to come to Houston in August.

    9. 04-24-2006 08:30 AM #9
      I've been, and it's too much for me. Thats one way to test it.

    10. 04-24-2006 04:02 PM #10
      I posted this in the Jetta IV forum... any help would be appreciated as well....

      Hi all,

      I have a 2000 Jetta GLX VR6 that's having AC problems. The stealership said that I needed to replace the large cooling fan as well as the high pressure switch to get the AC functioning again.

      I read a bunch of posts re: replacing the large cooling fans and troubleshooting them. This weekend, I replaced the large fan after confirming that it was indeed dead. Now however, neither of the fans come on when I start the engine. If I bridge the thermoswitch, the fans come on just fine (both speeds), however when I start the engine, neither of the fans come on. Does the AC high pressure switch have any affect? It only detects the freon pressure and turns off the compressor if the pressure is too high. Could the thermal Switch on the radiator be bad? What else can I check?

      Thanks,
      Neil
      2000 Jetta GLX


    11. 04-25-2006 02:39 PM #11
      This may shed some light on your situation, but my fans finally came on yesterday after months of being dormant. Turns out everythings fine. The reason I got concerned was that for some reason I thought that the fans came on whenever the engine was running. I guess this isnt the case. As for your situation, maybe you dont have a problem with the fans. If they operate when the thermoswitch is bridged, and the rad fan switch, then my guess would be that the fans are in working condition.

    12. Member ricardo's Avatar
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      04-25-2006 03:16 PM #12
      the fans only come on at a pre-determined temp 80C? Im going by memory here...do a search
      "Public transportation......because you're poor"
      done everything that's cheap....broke the most expensive parts....

      having cooling problems? check this out http://the-corrado.net/forum/viewtopic.php?f=1&t=68720

    13. 04-25-2006 04:01 PM #13
      I am going to see a fellow Vortexer tonight who has a VAG tool. Hopefully that will shed more light on the situation.

      Thanks


    14. Member ricardo's Avatar
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      04-25-2006 06:58 PM #14
      1H0 959 481 B Auxiliary Fan Switch
      Auxiliary Fan Switch
      Auxiliary Fan Switch
      Audi
      TT 2000-03
      TT Quattro 2000-03

      Volkswagen
      New Beetle 1998-02
      Corrado 1994-95
      Golf 1993-02
      Cabrio 1995-02
      Jetta 1993-02
      Passat 1995-97

      Note: Fits all motor sizes and is the OEM Temp(95-84/102-91c ).

      "Public transportation......because you're poor"
      done everything that's cheap....broke the most expensive parts....

      having cooling problems? check this out http://the-corrado.net/forum/viewtopic.php?f=1&t=68720

    15. 04-25-2006 07:24 PM #15
      should the rad fans run at 2 different speeds when bridging power to the other 2 connectors at the fan switch. my fans are on ly working at the first speed

    16. 04-25-2006 08:33 PM #16
      Somehow the AC compressor decided to work today, so I jumped out of the car, opened the hood and saw that both fans were spinning away. Next step is to order the High pressure switch and then go from there.

      The air temp was around 65 which is probably why the AC compressor cycled on. When it heats back up to the 90's, I'll take a closer look at the fans. In the meantime, I need to get a VAG read out.

      Thanks again for the help.


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