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Thread: Fan Speed 3 Not Working

  1. #11
    Senior Member Bitsyncmaster's Avatar
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    Someday I need to look into replacing that resistor with a PWM circuit. My new Toyota has a lot of fan speeds so I guess it has PWM.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  2. #12
    Senior Member DMC-81's Avatar
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    Quote Originally Posted by Bitsyncmaster View Post
    Someday I need to look into replacing that resistor with a PWM circuit. My new Toyota has a lot of fan speeds so I guess it has PWM.
    After needing to ask my friend Google what PWM means, I think this would be great.

    For other readers: "PWM = Pulse-Width Modulation. A modern duty cycle control allowing fans and pumps to perform on demand. Unlike voltage control PWM control actually lowers power draw."

    You are an electrical wizard Dave!
    Dana

    1981 DeLorean DMC-12 (5 Speed, Gas Flap, Black Interior, Windshield Antenna, Dark Gray)
    Restored as "mostly correct, but with flaws corrected". Pictures and comments of my restoration are in the albums section on my profile.
    2006 Dodge Magnum R/T (D/D)
    2010 Camaro SS (Transformers Edition)

  3. #13
    Senior Member Bitsyncmaster's Avatar
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    Quote Originally Posted by DMC-81 View Post
    After needing to ask my friend Google what PWM means, I think this would be great.

    For other readers: "PWM = Pulse-Width Modulation. A modern duty cycle control allowing fans and pumps to perform on demand. Unlike voltage control PWM control actually lowers power draw."

    You are an electrical wizard Dave!
    Yes PWM turns power on and off fully so there is no heat generated. A resistor or analog design produce a lot of heat.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  4. #14
    Junior Member
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    Quote Originally Posted by Bitsyncmaster View Post
    Yes PWM turns power on and off fully so there is no heat generated. A resistor or analog design produce a lot of heat.
    Anyone done this mod yet? Looks like it'd be under $20, considering you can switch 60A for $22: https://www.amazon.com/dp/B07B4B2X35..._1mV6CbZ64NR8N
    How many amps is the blower?

    I ask because my blower stopped working :-) My symptoms are a little weird... none of the speeds spin, but a volt meter at the blower wires shows 8V (with no load) on speeds 1 and 2, and 0V on speeds 3 and 4. My relays look fine, and resistor pack has a little rust but seems to test OK. Circuit breaker has continuity. When I got into the center console I found that the grounding post right next to the fan switch had come lose, but I got that all tightened up and no change. I guess it's my switch?

    -Mike

  5. #15
    Senior Member Bitsyncmaster's Avatar
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    Quote Originally Posted by nerdvana View Post
    Anyone done this mod yet? Looks like it'd be under $20, considering you can switch 60A for $22: https://www.amazon.com/dp/B07B4B2X35..._1mV6CbZ64NR8N
    How many amps is the blower?

    I ask because my blower stopped working :-) My symptoms are a little weird... none of the speeds spin, but a volt meter at the blower wires shows 8V (with no load) on speeds 1 and 2, and 0V on speeds 3 and 4. My relays look fine, and resistor pack has a little rust but seems to test OK. Circuit breaker has continuity. When I got into the center console I found that the grounding post right next to the fan switch had come lose, but I got that all tightened up and no change. I guess it's my switch?

    -Mike
    I recall testing my blower on fan speed 4 at 26 amps.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  6. #16
    Administrator Ron's Avatar
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    "60 A"!


    If you didn't load the thermal breaker during your tests, you might try jumping the Brown (N) wire to the Pink/Black (K/B) wire at #4 relay's socket...

  7. #17
    Junior Member
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    Quote Originally Posted by Ron View Post
    If you didn't load the thermal breaker during your tests, you might try jumping the Brown (N) wire to the Pink/Black (K/B) wire at #4 relay's socket...
    So I feel like an idiot. It was the fuse “ac mode selector”, not “panel lights”, and it was mostly-blown, leaving enough connection to give me voltage readings, but not enough current to drive anything, including relays. I went on a really uncomfortably hot road trip and I even had the spare fuses with me, if I’d just checked closer.

    Anyway, I still want to give PWM a try, but would be neat if there is a way to do it without permanently altering any wiring. Maybe replace the speed-4 relay with a wire so its always on and making use of the circuit breaker, then attach the pwm board to that wire, and try to find a way to get the heatsink of the board up through that little vent opening that the resistors are hiding in? (I assume those resistors are in there to take advantage of forced airflow) Then tuck the original switch back under the radio and put the potentiometer in its place?

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