Help with reversing salvaged 12V 4pin Fan from device

Projects General Guidance
1

Hello all,

As the title says, I need help with achieving a swap in direction for this 12V 0.68A EC reversible fan. I got it from an Airwoods ventilation device that got somewhat destroyed, so of course, I broke it apart to see what parts I could save for my projects. I'm interested in the fan (it only has one) because it is very strong and is designed to change directions. Honestly, with the summer over here, I have a few uses for it, but I'm particularly interested in changing its direction.

I'm a bit inexperienced with these types of fans. This one has 4 pins (see image), which, based on the colors, I'm guessing are: red (V), black (G), yellow (tachometer), and blue (PWM). I tried inverting the source wires, hoping it would help, but it just didn't start. I know for a fact that this thing is reversible; I've seen it work with just the panel powered.

I'm thinking maybe the yellow wire isn't a tachometer but another control pin to change directions. I tried applying 5V (high signal) via an Arduino pin and a low signal on this yellow wire, but neither worked.
PWM is not an issue and honestly not important right now.

Any help is greatly appreciated !!

Fan and panel view:

4080×1884 558 KB

2

Wonder if that burned it out.
In any case it's controlled by PWM. Duty cycle over 50% is forward less is reverse.

3

The fan still works fine. I will try with the Duty cycle, I'll reply with what I find, In the meantime any other idea or advice is appreciated.

4

Most fans require a PWM frequency between 10kHz and 25kHz
You may want to use the AVR_PWM library to set-up the frequency

5

It was in fact the intervals of duty cycle ! although its not as exactly as above or below 50% I can find the sweetspots myself. Thanks a lot man, would 100% buy you a beer for this.

6

Glad it worked
Have fun!

7

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.