I was try to hack a small blower to suck air instead of blowing air
From what I recall, reversing the supply is the way to go. But it seems that the blowers simply does not move.
Here is a link to the product page: https://robu.in/product/7530-12v-dc-blower-cooling-fan/
Is there some internal aspect of the mechanism that is preventing it from rotating in the other direction
Thanks in advance!
The way to turn a centrifugal blower into a vacuum is to attach a suction duct to the center port. There is no other way, reversing the motor won’t work.
This is because this kind of blower works by accelerating air radially, from the impeller center to edge into the ‘scroll’ (volute). It doesn’t matter so much which direction the impeller is spinning, radial acceleration still happens, although it will be more efficient in the preferred design direction than in reverse.
The inverse of a blower is a turbine: high-velocity/high pressure air enters at the edge into the volute, which accelerates the impeller from edge to center, leaving the center port at lower pressure and velocity. Combine the two, and you get the main plot device for a cheesy Vin Diesel movie franchise. Or a reason to buy a certain Subaru.
Anyway...
You asked why the motor didn’t spin.
In this blower, like most low-voltage DC fans, the motor is brushless DC. They do this to increase the life of the motor. Brushless DC fan motors, unlike brushed motors, are designed to work on only one input polarity because the supply powers the control IC and drivers, and it’s only required to work one way.
You may have fried it by connecting it in reverse, or if you’re lucky, the controller board had some built-in protection.
At any rate, as you saw, the motor didn’t spin.
Is it possible to make a reversible fan? Sure, an axial type with a brushed motor, or a BLDC with a reverse capability could do that (if they existed) by changing the phase sequence to the motor coils. That’s basically what a ceiling fan does, be it an older AC motor or more modern brushless DC type.
But not this fan, which can only do suction at the inlet and pressure at the outlet.
Most DC blower and fan motors use brushless DC motors with an electronic controller internal to the fan.
They are not reversible by reversing the supply, you may have destroyed the electronic controller.
In addition a centrifugal blower such as used here will not work effectively in the reverse direction even if the direction of rotation did reverse.
