328 Cooling Fan Mystery...getting 12 volts but not running | FerrariChat

328 Cooling Fan Mystery...getting 12 volts but not running

Discussion in '308/328' started by mtmilam, Sep 29, 2010.

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  1. mtmilam

    mtmilam Formula Junior

    Oct 24, 2009
    440
    Lafayette, LA
    Full Name:
    Mark Milam
    OK, This is for the Brain trust of the forum here....I have a 86 328, the Left fan Runs when temp gets over 190 or so....The Right fan won't come on, even with the AC switch turned on....BUT, 12.4 volts is getting to the FAN as measured with a voltmeter on the unplugged Spade connectors, going to the fan motor....

    Well...I thought it must be a Dead Fan Motor, so I finally found one (unobtainable) from a parted out Mondial.....I hooked a 12 volt battery to test the "new" fan.... it worked perfect

    Took my old fan out and just for ****s and Giggles, I hooked up a 12 volt battery and and touched the wires to the Old fan motor and it SPUN Like NEW.....WHAT The .....

    Sooooo...my fan motor is good, BUT it wont run when I plug the Spade connectors to it......EVEN though the Spade connectors are getting 12 volts from the car..

    ANY IDEAS as to what's going on????? I can't see why when I touch the Test probes from the multimeter to the spade connectors, I get 12 volts, but put the spade conn. back onto fan and motor doesn't run......Put Separate 12 volt battery wires to fan and it Runs like new....WIERD....HELP. :D:D
     
  2. wolftalk

    wolftalk Formula Junior

    Jan 27, 2004
    367
    san franciso area
    Full Name:
    phil
    measuring the voltage proves there's no open circuit, but it doesn't test that there's no excess resistance in the circuit that will drop the current so low that the fan won't run.

    in other words, you probably have a cruddy connection somewhere along the way. No current flow = no voltage drop across the bad connection.

    try connecting the fan and back-probing the connector (if possible, I forget), or use some jumpers that let you measure the voltage with the fan connected. Assuming you see a much lower voltage, you'll have to check other connectors in the circuit to find the bad one.
     
  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,038
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #3 Steve Magnusson, Sep 29, 2010
    Last edited: Sep 29, 2010
    What Phil said!

    I'd recommend that you unplug/inspect/reseat the "v" white connector on your fuse-relay panel (it's one of the three vertical ones) and inspect the connections for the A (light blue) and AN (light blue/black) wires (and it wouldn't hurt to unplug/inspect/reseat all of the the white connectors just to make sure you get the "v" connector). If those all look OK, the N (black) wire on each water fan motor is the ground -- so use a jumper wire to connect that terminal on the motor directly to the "-" battery terminal and retest.
     
  4. Iain

    Iain F1 Rookie

    Jan 21, 2005
    3,257
    UK
    I would also disassemble the motor - its not that hard to do & clean the cummutator ring and the brushes. Indeed you may find that it just needs new brushes. When I checked mine a year or so back there was a lot of crap in there.
     
  5. icecar-1

    icecar-1 Formula Junior

    Dec 5, 2008
    270
    Topsfield/Danvers Ma
    Full Name:
    Steve
    I had the same problem with my fan. It was a broken wire inside the insulation and would show voltage when tested but when installed on the fan the angle prevented a complete circuit. Wiggle the wire when testing and see if he test light flashes, if it does then you found it...
     

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