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Potentiometer Fan Speed Control

Discussion in '40- & 55-Series Tech' started by Ultima RB, Aug 10, 2005.

  1. Ultima RB

    Ultima RB

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    My half speed setting on my heater fan doesn't work. The resistor is busted. Instead of just replacing the resistor I want to fit a potentiometer so the fan speed is adjustable in more than just 3 stages (off, half, full). Are there any eletronic guru's who know how to wire this up?
     
  2. Steve C

    Steve C

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    You would want to wire the potentiometer with one leg to the low speed terminal of the heater switch, and the center tap of the potentiometer to the high speed terminal of the heater switch.

    A word of caution though, you are going to need a BIG potentiometer to disapate the heat.
     
  3. Stumpalama

    Stumpalama Forum Junkie SILVER Star

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    I was looking at doing the same thing... Did it work out for you? If so, what were the specs of the poteniometer you used.
    I figure there has to be a way to make this work, as most other cars use this style of fan control.
    Could you run it thru a relay instead?
     
  4. Coolerman

    Coolerman SILVER Star

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    Just replace the resistor. You will have a hard time finding a pot that can handle the current the heater will draw. If you want to really dig into this, a pulse width modulated controller with the ability to handle high current will do the trick. Search on DC motor control you will get all kinds of hits.

    Here is a kit you can buy that will do the trick: http://tinyurl.com/rd9j
     
    Last edited: Apr 28, 2006
  5. Advent

    Advent

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    What about taking the heater control knob out of another vehicle?

    Some of them seem pretty modular and might make for a pretty slick install into a refreshed dash.
     
  6. Stumpalama

    Stumpalama Forum Junkie SILVER Star

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    Exactly what I was thinking... updating the dash controls without trashing the simplicity or look of the dash itself.
    Where are the electronic tinkerers when we need them?
     
  7. Coolerman

    Coolerman SILVER Star

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    The heater controls in more modern vehicles with an infinite fan speed control use the same type PWM control as I posted. You would need to get not only the dash control but all the associated wiring and control modules. It can be done. Go raid a junkyard! Another solution if you simply want more speeds is to get 4 50 watt resistors of different values like 1,1.5,2,2.5 ohms (Available from www.alliedelec.com or Digi-Key for about $8.00 each) and connect them to a high current 4 position switch. This would double the speeds available in the Cruiser.