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Thread: PMW Fan Issues

  1. #1

    Default PMW Fan Issues

    PMW fan shows 10% when it's at 100%, and 90% when it actually at 10%. Fan works great, but when the fan is blowing 100% it shows 10%. I have to set it to 10% when I want it to be running 100%. If I want the fan to blow 10% I set it to 90%. Not sure what I've done? Any suggestions? Thanks, Glen

  2. #2


    Glen, which fans are you using? Andrew

  3. #3
    Join Date
    Nov 2014
    Ont. Canada


    And which controller are you using? And did you Pin Map it to a PWM+ or a PWM−?

  4. #4


    It's a Spal ABL506P.

    I tried three controllers. First one was used. Second one was a new Ford unit. Third one was a new Corvette unit. None of them would do anything. I called Spal and a tech told me I didn't need a controller. I wired it as per him. Large black to battery ground. Large red to battery positive and small yellow to PWM-. As soon as I set the temperature low enough it came on. I scaled it to 50% and it worked. I set it to 10% thinking it would slow down, but it sped up. I set it to 90% and it slowed down.
    I've read and watched Andrew's videos, set everything like that. It works great, just the percentage is backwards. Thanks for the response.

  5. #5


    Call them back and ask for the duty cycle vs. speed curve. They should provide one for you. Some of the new SPAL fans operate in the manner that you experienced, meaning a reverse duty cycle curve, high duty cycle is off and speed increases as the duty cycle decreases. SPAL should give you the exact numbers. Andrew

  6. #6


    Thanks Andrew. I'll do that and let you know. Thank you!

    85% is minimum, and 8% is maximum. Maybe this is what you need? Thank you again. Glen

  7. #7


    Quote Originally Posted by Hale584 View Post
    Thanks Andrew. I'll do that and let you know. Thank you!

    85% is minimum, and 8% is maximum. Maybe this is what you need? Thank you again. Glen
    Perfect. Just use that information to program your fan speed. I would use 80% for OFF, and not go under 8% for full speed. Did they say anything about the frequency? Andrew

  8. #8


    Yes, 128 is good. Thanks for the replies. It works great just backwards, but as long as it works I can get used to the numbers.

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