help finding resistor value suction fan motor | FerrariChat

help finding resistor value suction fan motor

Discussion in 'Mondial' started by bigeasy, Aug 20, 2017.

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  1. bigeasy

    bigeasy Formula Junior

    Dec 31, 2012
    368
    #1 bigeasy, Aug 20, 2017
    In the process of removing and repairing all things a/c related. I noticed my suction fan was not operating. it appears to spin easily by hand, but when jumped it I could not get it to spin. there is a resistor on the end of it, but it is discolored and cannot read what resistance value is normal? I did get a reading of 68.4 ohms. but didn't know where to find the correct value for this component. wanting to know what operating the system temporarily without the suction fan would do, I do have the sensor in place but removed the pump. Since this fan runs all the time, can't imagine how it could have lasted 33 years. I can image there are numerous non-functioning fans out there in our cars due to the age and constantly running. Just imaging what the internals of this suction fan would look like if it was in a car where the driver was a smoker...Thanks.
     
  2. bigeasy

    bigeasy Formula Junior

    Dec 31, 2012
    368
    #2 bigeasy, Aug 20, 2017
    84 Mondial qv cab
     
  3. bigeasy

    bigeasy Formula Junior

    Dec 31, 2012
    368
    #3 bigeasy, Aug 20, 2017
    Last edited by a moderator: Sep 7, 2017
  4. mello

    mello F1 Veteran
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    #4 mello, Aug 20, 2017
    68 ohms is a standard value for a resistor, so it's a good chance that you can replace it and it will work. Personally, I would increase the wattage rating of the replacement resistor.
     
  5. bigeasy

    bigeasy Formula Junior

    Dec 31, 2012
    368
    #5 bigeasy, Aug 20, 2017
    Thanks, it is currently showing 68.4 on my DVM, but it looks burnt. do I need to cut it loose from the circuit , at least one end, to get a correct reading? I just touched both leads of the DVM to the two ends of the resistor as it shows in the photo ?
     
  6. mello

    mello F1 Veteran
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    #6 mello, Aug 20, 2017
    I would cut one end of the resistor and remeasure to get the value. I can't tell what's the wattage rating of the resistor since there's no frame of reference. What's the length of the resistor body?

    There's also a tolerance value that needs to be considered and is identified by the fourth color band.

    silver = 10%
    gold = 5%

    If the fourth band is unidentifiable, a good guess is that it's a 10% resistor.
    Since the resistor is burnt, it begs the question as to why. My experience tells me that the motor bearing is probably shot. Do you feel any lateral play on the motor shaft? A shot bearing will cause the motor to work harder and draws more current. The extra current draw exceeds the resistor wattage rating, causing it to heat up and burn out.
     
  7. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
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    Steve Magnusson
    #7 Steve Magnusson, Aug 21, 2017
    +1 -- Also, this will let you measure the "resistance" of just the motor itself (it should not be infinite ohms, but rotate it a little by hand when making the measurement to rub the brushes onto different parts of the commutator).
     

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