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Thread: Auxiliary fan not coming on

  1. #1
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    Auxiliary fan not coming on

    I have noticed that my auxiliary fan is not coming on when I turn the AC on. I did notice that the fuse in slot 41 (aux fan) was blown although the fuse did have the wrong rating (15 instead of 30A). I have replaced this but it still does not come on.

    My questions are as follows.

    Am I correct in saying that the Aux fan should come on when I switch on the AC?

    Does anyone have any idea where I would start to troubleshoot this?

    My AC does not seem to blow cold air. Is there anything else I should be looking for?
    1998 M3 Evolution Convertible

  2. #2
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    Try just spinning it by hand and see if it wants to move first.
    Z3 - S50 - OBD2 - Smog Legal - 6 Speed - 3.46 - Anthracite

  3. #3
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    The factory manual has a nice procedure to test it by shorting the wires at the radiator coolant switch; might search for it, as I don't have it memorized. It's nice because it tests both the high and low speed fan ops (incl relays); plus it's super-easy!
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  4. #4
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    OK,
    I tried moving the fan with the engine off and it wouldnot budge. I also tried crossing the temp sensor wires (as in bentley manual) and I could hear the motor straining and then the fuse blew. I'm guessing I need a new auxiliary fan motor.

    Gonna order one.

    Thanks for the help
    1998 M3 Evolution Convertible

  5. #5
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    You may just have a rock or road pebble stuck in the motor. Brand new these fans are 300 plus. . . .. I'd take it out and spray it with electric motor cleaner first to see if that fixes the problem. Just an option. . . .


    K

  6. #6
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    97 M3/4/5 07 Ram2500 CTD
    My Aux fan wasn't coming on last summer. The fan clutch was the culprit. They just wear out over time. The new clutch wasn't too expensive and it was a pretty quick fix.

    Dinan CAI, Conforti Shark, Tein Basic C/Os, 8.5" Squared DSII wrapped in Star Specs, Euro Floating Rotors. WTB: Trunk w/ no spoiler, ZKW Headlights, Exhaust (Dinan or UUC RSC36)

  7. #7
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    check fan clutch, that sounds like the prob since teh fan is locked up. If that doesn't do it then you need the temperature switch that plugs into the passenger side of the radiator. Like $25 from Pelicanparts.

    Dinan CAI | Dinan MAF | Dinan Exhaust | Dinan Stage 4 Engine Software | 19" Staggered M Par Reps | Rear Lip Spoiler |

  8. #8
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    Quote Originally Posted by dcroghan View Post
    check fan clutch, that sounds like the prob since teh fan is locked up. If that doesn't do it then you need the temperature switch that plugs into the passenger side of the radiator. Like $25 from Pelicanparts.
    The Fan Clutch and the A/C Aux Fan are completely separate . . . . at least they are on my e36 325i. I don't own an M3 but I imagine they are separate as well.

    He has already diagnosed that the A/C AUX FAN is getting power (audible sound) but seems to be stuck. I recommend taking out one of your kidney grills and try spinning the fan by hand. If a small rock or debris is is there it may force it out. It really is not a hard fix and believe me you'd be PO'd if there is nothing wrong with your A/C AUX Fan when you shell out 300 bones for a new one.

    Let us know what you find.


    K

  9. #9
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    Quote Originally Posted by kablammo View Post
    The Fan Clutch and the A/C Aux Fan are completely separate . . . . at least they are on my e36 325i. I don't own an M3 but I imagine they are separate as well.

    He has already diagnosed that the A/C AUX FAN is getting power (audible sound) but seems to be stuck. I recommend taking out one of your kidney grills and try spinning the fan by hand. If a small rock or debris is is there it may force it out. It really is not a hard fix and believe me you'd be PO'd if there is nothing wrong with your A/C AUX Fan when you shell out 300 bones for a new one.

    Let us know what you find.


    K
    Well, I took out one of the Kidney grills and gave it another go at trying to free up the fan and it snapped off the motor in my hand. I have not taken the bumper off yet to get the whole fan out as I don't have a garage and it was getting late/dark here. The plastic seemed very brittle and from what I can see I will need a new motor as it is attached to the fan (or at least it was). Am I correct in saying so? Looking at the part online it seems to come in one piece. Part number 4 (Pusher Fan)



    I will hopefully have a second hand fan tomorrow, not going to shell out for a new one.

    I agree with kablammo on the clutch thing, the aux fan is electric and is in front of the radiator, seperate to main fan.
    Last edited by ecooney; 04-14-2008 at 07:01 PM.
    1998 M3 Evolution Convertible

  10. #10
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    Jeep ZJ, 95M3
    I am seeing a similar issue:
    http://forums.bimmerforums.com/forum...d.php?t=981398

    but my fan does spin freely.

    also the motor does come apart from the fan. i have an extra one i can sell you if you're interested.
    Mods: Eibach Sways, xbrace, JC chip, jtd underpanel, ssk

  11. #11
    Join Date
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    OK,
    I put the new fan in (well got a second hand one out of a lightened M3).
    Anyway the fan is now in but I have noticed that when I turn on the car the temperature on the OBC is reading -30 degrees Celcuis. I have reconnected the temp sensor in the brake duct after I removed it. The only thing I can think of is that I have damaged it somehow on removal (although I only disconnected it) or that it needs to be reset after it is reconnected.

    Any help here would be appreciated.
    1998 M3 Evolution Convertible

  12. #12
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    Temperature sensor working now, must have needed time to reset.

    Next question is,

    What would be the cause for the auxiliary fan not coming on?
    I've tested it off the radiator connector and low and high is working.

    I'm guessing it is either the radiator sensor or further problems with the air-con.

    Any ideas???
    1998 M3 Evolution Convertible

  13. #13
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    95 Cosmos M3...
    I just tried my A/c for the first time today and my auxiliary fan is not working.So I guess I,ll be checking mine out next week.I know soon as i turned the A/c on the 318 the fan would start right up.

  14. #14
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    My aux fan (not the clutch driven fan) stopped working a couple years ago. The car would slowly start to overheat on 90 degree days in stop-no-go traffic and autox

    I just bought a 80$ SPAL electric fan and wired it in. It's pretty easy to do.

  15. #15
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    Mine didn't work at first, all it needed was a new fuse. Been fine for over 2 yrs now. And know that just because a fuse can read ok on a multimeter when in fact it cannot pass enough current. (Amps. High current items like motors can slowly errode the wires in fuses and breakers) So try giving it a new fuse before moving on to other things....

    John
    '95 Hellrot M3 w/Dove
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  16. #16
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    Quote Originally Posted by MyMach5 View Post
    My Aux fan wasn't coming on last summer. The fan clutch was the culprit. They just wear out over time. The new clutch wasn't too expensive and it was a pretty quick fix.
    The Fan Clutch has absolutely, positively NOTHING to do with the operation of the Aux fan! The fan clutch controls the operation of the MAIN cooling fan!Come on guys..this forum gives out a TON of bad information. Between "replace every OEM bushing with poly for a better ride" and "do the fan delete mod and rely on the AUX mod to save your motor in the event of an overheat", it's hard to tell whats good info and crap lately.

  17. #17
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    So if I don,t get this fixed I will be overheating this summer?

  18. #18
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    Quote Originally Posted by JETninja View Post
    Mine didn't work at first, all it needed was a new fuse. Been fine for over 2 yrs now. And know that just because a fuse can read ok on a multimeter when in fact it cannot pass enough current. (Amps. High current items like motors can slowly errode the wires in fuses and breakers) So try giving it a new fuse before moving on to other things....
    Thanks!First thing i checked and the fuse was shot!.One question though does yours kick on and off all the time?

  19. #19
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    What Spal fan is everyone using?

    My aux is seized up, and I am not spending ~$300 for an OEM.
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  20. #20
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    Auxiliary fans cost an arm a leg to replace

  21. #21
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    Quote Originally Posted by mikese36 View Post
    Thanks!First thing i checked and the fuse was shot!.One question though does yours kick on and off all the time?
    Nope.....it works as its supposed too, when the A/C is on and or if the temp reaches a special point. I now run FDM which means a lower temp for it to come on, but it rarely does since my car is running a 3 row radiator from the Z3M. (stock is 2 row)

    Sounds like you may need a new temp switch.....

    John
    '95 Hellrot M3 w/Dove
    AA Euro HFM Stage II (w/21# Injectors & Software) W/Gen III Exhaust - URI Crank Pully - FDM w/3 Row M Coupe Rad - 3.23 LSD - Vogtland Club Spec/Koni SA - UUC Red w/Enforcers - TMS Shims/Rear Camber Bars w/QA1 inners/Sways - VMC F/TMS R End Links - X-Brace - Perf Ultimate/SS Brake Lines - GC Tower Mounts/RTAB Shims - ZKW's w/5000K Hid - Fog Delete - Alpine 9847/Pioneer TS-C130R Kevlar Components/Pioneer PRS-X340/Stealth Box's/Wired Zune 120GB - OE LTW CF Sills/Glove Box Plate - Staggered Black M-Spoke II's w/235/40 (front), 255/40 (Rear) Nitto NT05's - Rolled Fenders!

    ***Got a '95 M3? (actually pretty common on all years! Even happened to Racer Seth Thomas! ) Check Your LSD! http://forums.bimmerforums.com/forum...d.php?t=390209

  22. #22
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    I'm thinking temp switch also.
    My other question is that if the temp switch is faulty should the fan not come on when the AC is running?

    When I put the AC on the fan DOES NOT run. I'm just wondering if the temp switch is part of the AC circuit also or does it bypass it?
    Last edited by ecooney; 04-21-2008 at 02:01 PM.
    1998 M3 Evolution Convertible

  23. #23
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    Anyone?
    1998 M3 Evolution Convertible

  24. #24
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    So if the fan comes on when you short the connector I would start tracing back from there or start with a wiring diagram and go from there.
    Z3 - S50 - OBD2 - Smog Legal - 6 Speed - 3.46 - Anthracite

  25. #25
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    Quote Originally Posted by cabin View Post
    What Spal fan is everyone using?

    My aux is seized up, and I am not spending ~$300 for an OEM.
    I used:

    1 x Size 16" push / Part# 0401 $64.00

    That part # is for the fan on www the-fan-man com

    16" thin series

    It's the same one that is used on the technique tuning turbo kit.

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