Stir Plate Build - Computer Fan Won't Spin

[MrZuckerkorn]

I've been interested in getting a stir plate for a while, and after reading various DIY forums, figured I'd build my own. I went off of the build linked below, modifying for a cigar box:

https://www.homebrewtalk.com/showthread.php?t=86252

The only problem is that my fan won't spin! At first I thought that my cell phone charger wasn't strong enough at 4.5V for a 12V fan. So, I bought a stronger charger. That didn't work, so I assumed my fan was bad. I got a second fan, same model, and tried again, no luck. The fan is 12V, .36A, and my power supply is 12V, .2A. I also tried one that was 12V, .5A, still nothing. The power supply does say AC Adapter, but the output is listed as DC, so I'm assuming that it's compatible.

I'm attaching pictures with the wiring completed to show that the power source is powering the switch correctly (at least I assume, since the light is on), but I've also tried connecting the fan wires directly to the power supply. When I use my current detector, it appears that there is current throughout the system. It beeps quickly and continuously whether I touch it to the outlet itself, the switch, the rheostat, or the center of the fan.

Any tips out there, am I missing something completely obvious? Or are there certain fans that can't be used in this way? I did cut off the end of the fan wire, where the red and black went into a plastic plug and 4 wires came out, but I figured that was just for computer hookups, the red and black wires I'm using now run directly into the fan. This thing is driving me crazy and I'm tired of buying new parts to try out knowing that the second I cut the wire, I'm stuck with them!

 

[dude_brewery]

Does the fan spin when you hook its wires up directly to your DC power converter?

Edit: Also, if you haven't yet - try switching the wire connections at your on/off switch. You might have the polarity reversed (so that the electric current is running backwards through the fan). DC fans need to have current traveling in the correct direction, otherwise they won't spin.

 

[MrZuckerkorn]

I can try switching wires on the switch tonight. However, I did hook the fan up to the power adapter wires directly with no spin. The current detector beeps like crazy when I touch the center of the fan after doing this, but no movement. Seems like a broken fan, but after trying a second fan with the same results I'm not convinced.

 

[MrZuckerkorn]

Well, the culprit was a defective fan. I guess the lesson here is that if you're pretty sure a part is broken, replace it with a new part, and it still doesn't work, replace it again. The yeast is happily multiplying in preparation for today's brew session!