2008 XC90 V8 radiator fan always on
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    1. #1
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      2008 XC90 V8 radiator fan always on

      I picked up a 2008 V8 a few months ago and I'm enjoying the car.

      I've noticed that the radiator fan comes on almost immediately after start up and turns off once I shut the car down. Sometimes it stays on a few minutes after shut down.

      I have flushed the coolant and replaced the thermostat, but didn't expect that to have any effect. The interior HVAC has acted wonky a few times as well... driver side blowing cold halfway through a trip while passenger works normally (with heat on as temperatures are cold in CT).
      Not sure if they're related. The temperature needle moves up to the center and stays there when the car warms up. Any sensors to check out that may be causing this? Unfortunately I don't have VIDA or the diagnostic tool.

      Thanks in advance!

      Here she is next to my Great Dane.
      Last edited by davidx1994; 11-20-2019 at 11:47 AM.

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    3. #2
      Junior Member PDLarson's Avatar
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      Search here or Google for XC90 radiator fan. Lots of issues but the controller is self contained in the fan assembly so the fix if it's not working right is easy... replace the entire fan assembly.
      New Volvo part is ~$500
      New aftermarket is ~$200
      I have a contact at a junk yard who ordered me a used one from another yard for $100 shipped. Works great!

      Pain in the ass to replace though. Have to lower the radiator from underneath then you can lift the fan out. Take your time putting everything back together.
      Pro tip: when the instructions say check function of good latch release before tightening bolts and closing the hood, do that
      Otherwise you'll be learning how to release one or both latches from under the car.

      Sent from the demons in my head
      Quote Originally Posted by buycurious View Post
      ultimately the problem was just as pdlarson had predicted...
      1999 V70XC / Mostly stock under the hood / Several cosmetic mods inside and out
      2008 XC90 V8 Executive

    4. #3
      Junior Member Orange's Avatar
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      I'm not aware if the regulator is bad - good to test it - but I have already replaced mine by simply cut the two thick red wires, swapped with a used unit from the junkyard, and soldered the wires back. Worked fine for the past 4 years. There are two large capacitors inside, I know some radiators don't have this regulator fixed on them, not sure how's the V8 one
      Also see if maybe the A/C compressor clutch is stuck running, this may also activate the radiator fan

      .
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    6. #4
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      If you are running your defrost, it will kick on the AC to help dehumidify and run the engine fan.
      2004 XC90 2.5T FWD + 2006 XC90 2.5T

    7. #5
      Member ggleavitt's Avatar
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      What suggests the engine cooling fan is not working properly? Sounds like it comes on and turns off (just like it should), as based on the PWM waveform produced by the ECM.

      Not sure I'm following.
      2005 XC90 B5254T2 019 198k
      2008 XC90 B8444S Sport 452 127k

    8. #6
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      Quote Originally Posted by ggleavitt View Post
      What suggests the engine cooling fan is not working properly? Sounds like it comes on and turns off (just like it should), as based on the PWM waveform produced by the ECM.

      Not sure I'm following.
      On a cold / cool day, an engine cooling fan kicking on just a few minutes after start-up and never shutting off until the ignition is turned off would strike me as unusual.
      2009 XC90 3.2 AWD l Oyster Grey / Bi-Xenon / Dynaudio / BLIS / VNS / RSE / THULE Aeroblade

    9. #7
      Junior Member PDLarson's Avatar
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      As mentioned above, running the defrost uses the A/C compressor which can trigger the fan.
      In your first post you mentioned it runs after shutting off the engine, that in itself is not unusual either.
      I stopped trying to guess what my V8 XC90 is doing a long time ago.
      I replaced my fan when it would never run and the car overheated.

      Sent from the demons in my head
      Quote Originally Posted by buycurious View Post
      ultimately the problem was just as pdlarson had predicted...
      1999 V70XC / Mostly stock under the hood / Several cosmetic mods inside and out
      2008 XC90 V8 Executive

    10. #8
      Member ggleavitt's Avatar
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      Quote Originally Posted by ShadowDancer View Post
      On a cold / cool day, an engine cooling fan kicking on just a few minutes after start-up and never shutting off until the ignition is turned off would strike me as unusual.
      See VIDA- 2006 XC90 V8, Design and Function- 284: Engine control module (ECM), B8444S /Engine cooling fan (FC) / Engine cooling fan (FC) control module.

      The 6-speed engine cooling fan will run while engine is on and will continue to run for some time after engine is shut down and ignition key has been removed. Couple notes in VIDA specific to this statement, up 6 minutes post run depending on conditions.

      Maybe it's more fun to "guess" how this is supposed to function, VIDA is pretty clear how it actually does.
      2005 XC90 B5254T2 019 198k
      2008 XC90 B8444S Sport 452 127k

    11. #9
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      Quote Originally Posted by ggleavitt View Post
      See VIDA- 2006 XC90 V8, Design and Function- 284: Engine control module (ECM), B8444S /Engine cooling fan (FC) / Engine cooling fan (FC) control module.

      The 6-speed engine cooling fan will run while engine is on and will continue to run for some time after engine is shut down and ignition key has been removed. Couple notes in VIDA specific to this statement, up 6 minutes post run depending on conditions.

      Maybe it's more fun to "guess" how this is supposed to function, VIDA is pretty clear how it actually does.
      GG, you're doing it again...
      As I have written in a previous post, not everyone here has a VIDA/DICE unit. It is almost as if you assume all owners have invested in one?

      When a member, who is clearly a new owner, is trying to troubleshoot what they perceive is a problem [although not] and asks a question, when you lead-in with "Why would think that ... as based on the PWM Waveform of the magical unicorn all seeing eye. Not sure I'm following [why you think there's a problem.]", it has the effect of coming off, at worst, a little snooty and at best needlessly technical and speaking over the head to someone who at first blush doesn't seem to be technical nor need that level of detail.

      Not saying this is your intent, but, "It's not a problem. They all do this. This is the way Volvo wants it to work for the V8 model" is a tidy summation and gets to heart without the pointed lead.

      To most people familiar with vehicles, but who are not familiar with the particular ways in which Volvo does things, a cooling fan kicking on just after cold start and running the entire duration even after the ignition is shut off - again on a cold / cool day - would strike them as abnormal behavior based on their years of previous experience with other vehicles.

      When I first got my XC, I was caught by surprise by 'Afterblow' and thought my blower motor controller malfunctioned or a resistor failed and a hot wire was still feeding it power. It wasn't until I came here and dug around a bit that I discovered that was natural behavior to preserve the evaporator. Over time, I've become accustomed to Volvo doing it the Volvo way and to maybe not panic when I see / hear something that goes against the decades of ingrained car behaviors I expect.

      He will to ...
      Last edited by ShadowDancer; 11-21-2019 at 01:23 PM. Reason: Who doesn't like white space? I do. So I added some.
      2009 XC90 3.2 AWD l Oyster Grey / Bi-Xenon / Dynaudio / BLIS / VNS / RSE / THULE Aeroblade

    12. #10
      Member ggleavitt's Avatar
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      DICE is just the vehicle interface, the information is in VIDA and it's relatively easy to get an image installed on a working PC. Link here (again)- https://forums.swedespeed.com/forumd...ine-Management No VIDA or PC to install VIDA? Then clunk your way through this- https://workshop-manuals.com/volvo/


      My intent is ensuring that factual information gets published to the benefit of the greater audience, a review of my posts on Swedespeed and MVS over the last 14+ years should reflect this intent. I might have digressed a few times but there's overt consistency in the information that I post, more often than not providing direct links to my findings. Do the same and we'll be in alignment.

      *Adding link for owner manuals as well- https://volvo.custhelp.com/app/homeV3 for "new" owners.

      **Afterblow is specific to mitigating cabin odor (although I'll suppose a dry evaporator lasts longer than a moist one). See https://forums.swedespeed.com/showth...fterblow-stuff for more information.
      Last edited by ggleavitt; 11-21-2019 at 03:02 PM. Reason: *add owners manual link, **afterblow
      2005 XC90 B5254T2 019 198k
      2008 XC90 B8444S Sport 452 127k

    13. #11
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      For the avoidance of doubt I, and I'm sure many others, appreciate the depth, color, adherence to technical fact, and personal knowledge & experience you contribute.

      But sometimes when someone asks for the time, they don't want a rejoinder and instructions for how to build a clock ... they'd just like to know the time and a quick reassurance it's OK.
      2009 XC90 3.2 AWD l Oyster Grey / Bi-Xenon / Dynaudio / BLIS / VNS / RSE / THULE Aeroblade

    14. #12
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      Give a man the time and you answer him for a moment; teach a man build a clock and you answer him for a lifetime.

      (These days you also should teach them how to read a round clock. My kids understand 8:45 but not quarter to nine.)
      John C
      ---------------------
      2011 XC90 3.2 171,000 miles and counting...

    15. #13
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      Thanks guys! I won't worry about it anymore.

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