Radiator fan turns on more often/sometimes won't turn off
Results 1 to 15 of 15

This is a discussion on Radiator fan turns on more often/sometimes won't turn off within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; Have a 2004 WRX w/about 133,000 miles on it. Noticed recently that both radiator fans have been coming on more ...

  1. #1
    Registered User
    Join Date
    Jan 2010
    Location
    Loganville, GA
    Posts
    43

    Radiator fan turns on more often/sometimes won't turn off

    Have a 2004 WRX w/about 133,000 miles on it. Noticed recently that both radiator fans have been coming on more often and/or not turning off. The temp. gauge never goes above half way so the engine doesn't appear to be over heating...and it's also been real cool here and I have not been running the AC or defrost. And when I say both fans come on, they come on full blast and are kind of loud. Last time I noticed it happening was when I recently pulled into my garage so it was easy to tell they were on. Instead of turning the car off, I let it sit there and idle to see if they would turn off on their own. Even put the hood up to help. Let it idle for about 5 minutes and they still didn't turn off. The outside temp. was probably mid-60's at the time.

    I've searched around and the only thing I found close to what's happening with my car was in a Legacy GT forum and in most cases it turned out to be the ECU and/or fan relay. There was a TSB/recall for it but it only covered certain 2004 (maybe 2005 too?) Legacy and Outbacks. Could there be a similar problem with the WRX ECU's?

    This past summer my radiator cracked while we were out. It didn't loose a whole lot of coolant and we were able to drive it home without it overheating. The fans both came on (like they should) by the time we got home (temp gauge never went above half way the whole time). Ever since then (and having the radiator replaced) is when I seemed to notice the fan issue more often. Not sure if there's a relationship there or not.

    It seems to be more of an annoyance than anything right now, especially since the car doesn't appear to be over heating at all and the coolant level is more or less consistent. But I suppose the fan motors could fail quicker and I'm not sure if this would cause problems this summer when the AC will be in use. The other forum suggested things like removing the fan fuse so it turns off. Don't really want to do that. Would resetting the ECU help? Or should I just take it to my mechanic and see if they can find something. I really don't want to pay for a new ECU.

    Any help/suggestions would be greatly appreciated. Thanks.

  2. Remove Advertisements
    ClubWRX.net
    Advertisements
     

  3. #2
    He simply abides. SD_GR's Avatar
    Join Date
    Jul 2002
    Location
    CA, US
    Posts
    22,561
    I Support ClubWRX
    A fault in fan control logic ought to generate a CEL. If there is none I'd not know where to start, or even why, provided the car does not overheat as you say.
    WRX Info Links, Courtesy TheJ
    The world breaks everyone and afterward many are strong in the broken places. Ernest Hemingway
    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
    DISCLAIMER: Opinions expressed are the author's alone and are inherently worthless.

  4. #3
    Registered User
    Join Date
    Jan 2010
    Location
    Loganville, GA
    Posts
    43
    Quote Originally Posted by SD_GR View Post
    A fault in fan control logic ought to generate a CEL. If there is none I'd not know where to start, or even why, provided the car does not overheat as you say.
    Yea, you'd think. The guys over at the Legacy GT forum never got a CEL or anything when it happened. That's probably why when they took their cars to the dealer they couldn't really find anything either. Most of this was going on in 2005. Then Subaru came out with a TSB about it that said to check/change the fan relay and then check the ECU/ECM and replace if needed. That seemed to fix the problem most of the time according to the posters although a couple had to have 3 ECU's replaced in a matter of months because the problem would reoccur. So I'm guessing the relay would go first and if not fixed, would affect something in the ECU which would require the ECU to be replaced. I was just wondering if anyone with a WRX experienced the same problem as all the Legacy GT's/Outbacks.

  5. #4
    Registered User
    Join Date
    Jan 2010
    Location
    Loganville, GA
    Posts
    43
    Does anyone know the p/n for the fan relay? I know that Subaru uses the same relays for many different things. A quick search found p/n 82501GA240 and p/n 82501FC000. I'm thinking it's the latter, but not sure. Also, anyone know exactly which relay it is in the fuse box? Seems like an easy and inexpensive way to try to fix the problem. Just need to know which p/n it is and where it goes. Thanks.

    Reading the TSB for the Legacy GT's, it looks like there is a replacement relay (p/n 82501AG120). Wondering if that one will fix a 2004 WRX.

    BTW, here's a link to one of the threads on this subject at the other forum: http://legacygt.com/forums/showthrea...ble-40207.html
    Last edited by dttruax; 11-16-2012 at 06:35 PM.

  6. #5
    Registered User
    Join Date
    Jan 2010
    Location
    Loganville, GA
    Posts
    43
    Guess no one else seems to have this "problem". I've found out more of what is happening. It seems that the fan may be turning on when it's supposed to (based on coolant temp. and speed of the car), but doesn't seem to be shutting off when it usually would... except when you turn the car off. I've noticed that if you turn the car back on before the engine cools sufficiently, the fan will turn on at start-up. Otherwise only when the engine gets to temperature. I've also noticed that a little stop and go driving after a cold start up doesn't seem to trigger anything, but if I drive at speed (40-60+ mph) for a few miles (I know there's some boost at that speed/rpm) and stop at a light, I notice that the fan will be at high speed but will slow down to slow speed after a second or so and then will go back up to high speed (I think, kind of hard to really hear) when I get back up to speed. All this while it's been relatively cool outside here (anywhere from 35-60 degrees).

    As I said earlier, the temp gauge on the dash shows no signs of overheating. Neither does the engine really. No steaming, etc. So I'm not sure what, if anything, to do. Is it the fan relay? Coolant temperature sensor? Thermostat? ECU? Water pump? Combination of a couple? I did start noticing this around the time my radiator cracked, but my mechanic said he checked everything out after replacing the radiator and everything was working correctly. Of course that was in the summer and the fan is always on when the AC is on.... so who knows when it started and if the cracked radiator was a contributing factor.

    Any help/info would be greatly appreciated as this may be a tricky thing to diagnose.....

  7. #6
    He simply abides. SD_GR's Avatar
    Join Date
    Jul 2002
    Location
    CA, US
    Posts
    22,561
    I Support ClubWRX
    Well, hm... The water pump will work or not, and you have circulation and no leaks, so let's exclude that. Likewise the thermostat, provided you have circulation. The cracked radiator necessitated removing the fans, so it meant someone disconnected them. I'd check the fan harnesses and make sure all the wires are in all the way into each end of the harness clips etc. I'd suspect electrical at this point, so wires - harness clips - relay, in that order.
    WRX Info Links, Courtesy TheJ
    The world breaks everyone and afterward many are strong in the broken places. Ernest Hemingway
    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
    DISCLAIMER: Opinions expressed are the author's alone and are inherently worthless.

  8. #7
    Registered User
    Join Date
    Jan 2010
    Location
    Loganville, GA
    Posts
    43
    Quote Originally Posted by SD_GR View Post
    Well, hm... The water pump will work or not, and you have circulation and no leaks, so let's exclude that. Likewise the thermostat, provided you have circulation. The cracked radiator necessitated removing the fans, so it meant someone disconnected them. I'd check the fan harnesses and make sure all the wires are in all the way into each end of the harness clips etc. I'd suspect electrical at this point, so wires - harness clips - relay, in that order.
    Thanks. I'm thinking relay/ecu since, as you said, all the mechanicals should be gtg. Maybe coolant temp. sensor assuming the fans use a different sensor than the main sensor.... although I'm pretty sure the temp sensor connects directly to the ECU which then goes to the fans, etc. Is it possible that the coolant temp sensor could be starting to fail (ie, not sensing the coolant cooling down after fans run?) Hope it's not the ECU because that can be big money. Tried to see if the new re-designed fan relay that was for the Forester/Outback's that were having a similar problem a few years back would work, but it's a 5 prong relay whereas the WRX has 4 prong relays.

  9. #8
    He simply abides. SD_GR's Avatar
    Join Date
    Jul 2002
    Location
    CA, US
    Posts
    22,561
    I Support ClubWRX
    I do not know how to diagnose the temp sensor though, sorry. Before you get into the big $ stuff, make sure the connections are actually all OK, because it's suspicious that this all started when the fans were disconnected.
    WRX Info Links, Courtesy TheJ
    The world breaks everyone and afterward many are strong in the broken places. Ernest Hemingway
    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
    DISCLAIMER: Opinions expressed are the author's alone and are inherently worthless.

  10. #9
    Registered User
    Join Date
    Jan 2010
    Location
    Loganville, GA
    Posts
    43
    Quote Originally Posted by SD_GR View Post
    I do not know how to diagnose the temp sensor though, sorry. Before you get into the big $ stuff, make sure the connections are actually all OK, because it's suspicious that this all started when the fans were disconnected.
    I've read it can be done checking the resistance as the engine warms up. Supposed to be charts somewhere to tell you what the resistance should be at different coolant temps. Or could throw a CEL. A little above my paygrade. Also, they don't seem to be that expensive, but appear to be a pain in the butt to replace.

    But, I'm not exactly sure when this started happening. My wife drives it more than I do... and the fan is always on most of the time when the AC is on.....
    Last edited by dttruax; 12-03-2012 at 05:32 PM.

  11. #10
    Registered User
    Join Date
    Jan 2010
    Location
    Loganville, GA
    Posts
    43
    Well I had my mechanic check it out today and he said everything is working fine. The fans are turning on and off when they're supposed to. Hooked up to the computer and checked the coolant temp and all. He said it's possible that the engine as a whole may just be running a little hotter than it used to because it is older and does have 137,000 miles on it. Also said the mechanicals of the cooling system are working fine. Guess I won't worry about it too much unless it does start overheating.

  12. #11
    Registered User
    Join Date
    Jan 2010
    Location
    Loganville, GA
    Posts
    43
    Picked up the car this evening from my mechanic (they were closed). Got about 1 mile from my house and the check engine light came on. Ugh. Turned around and took it back. It seemed to be running fine on the way home... noticed that the radiator fan was on full again. So maybe this has something to do with all that. Guess I'll find out tomorrow when they pull the code.

  13. #12
    Registered User
    Join Date
    Jan 2010
    Location
    Loganville, GA
    Posts
    43
    Picked up the car tonight after having the pre-cat and front-cat replaced (got a good deal on some lightly used ones) so that problem might be taken care of. However, the radiator fan issue is not resolved. Not sure where to go to from here. Since I think I first started noticing it after I had my radiator replaced in the summer, I'm thinking of maybe replacing the thermostat with an OEM one and possibly using the blue Subaru coolant. My mechanic used the regular green stuff (and has been for awhile with my car).

    The interesting part of this issue is that everything is fine when you start driving. But after a few miles at speed (45+ mph) and the engine comes up to temp (again, no sign of overheating with the gauge on dash...) will the fans come on high. I notice this when coming up to a stop sign, etc. when I hear the fans go from high to low. Not sure what that means... but I guess it could mean the head gasket could be on the way out and some exhaust gases are getting into the coolant system at speed.... certainly hope not.

  14. #13
    He simply abides. SD_GR's Avatar
    Join Date
    Jul 2002
    Location
    CA, US
    Posts
    22,561
    I Support ClubWRX

    Radiator fan turns on more often/sometimes won't turn off

    The coolant will not make that difference though I've switched to blue also.

    If gasses are entering the coolant the head gasket has already failed. This is detectable and testable.
    WRX Info Links, Courtesy TheJ
    The world breaks everyone and afterward many are strong in the broken places. Ernest Hemingway
    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
    DISCLAIMER: Opinions expressed are the author's alone and are inherently worthless.

  15. #14
    Registered User
    Join Date
    Jan 2010
    Location
    Loganville, GA
    Posts
    43
    Quote Originally Posted by SD_GR View Post
    The coolant will not make that difference though I've switched to blue also.

    If gasses are entering the coolant the head gasket has already failed. This is detectable and testable.
    I guess I mean the green long life coolant from Subaru. Although as you said, I'm not sure the brand makes that much difference. Haven't had the Subaru conditioner added either. Not sure if that would need to be done or not.

    Thinking back I'm pretty sure my mechanic didn't use an OEM thermostat when it was replaced at 100,000 w/timing belt and water pump because if I remember correctly, it only cost like $5.

    The fact that, according to the gauge on the dash, the car is not overheating is what is stumping me. It would appear that the cooling system is doing it's job the way it's supposed to. If not, then it's probably a relatively easy and quick fix. However if it's something else, then maybe not.

  16. #15
    Registered User
    Join Date
    May 2011
    Posts
    1
    Quote Originally Posted by dttruax View Post
    I guess I mean the green long life coolant from Subaru. Although as you said, I'm not sure the brand makes that much difference. Haven't had the Subaru conditioner added either. Not sure if that would need to be done or not.

    Thinking back I'm pretty sure my mechanic didn't use an OEM thermostat when it was replaced at 100,000 w/timing belt and water pump because if I remember correctly, it only cost like $5.

    The fact that, according to the gauge on the dash, the car is not overheating is what is stumping me. It would appear that the cooling system is doing it's job the way it's supposed to. If not, then it's probably a relatively easy and quick fix. However if it's something else, then maybe not.

    I have been having the exact same issues with the fans on my 05 92X aero. I hooked up my AP to monitor the coolant temp with the fans off, let it idle till the the temp gets up to 212 or so, the fans kick on, the temp drops to 201 and stays there, the fans stay on full blast. If the temp drops down to 190, the fans kick off. I have the Lisle funnel for purging the cooling sys and have purged it 5 or six times and never get more than a few dozen pin sized bubbles, so i cant believe there are any bubbles in the system

    There are 2 temp sensors. one for the gauge on your dash and the other for the ECU. The one for the ECU, which i believe is what is displayed on the AP, is right behind the alternator in the coolant cross over pipe. It is my goal to change this out this weekend, along with rebuilding the PS pump that started spewing fluid.

    What is your plan of attack?

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •