I noticed that the small fan never turns on under normal conditions.
The error code reader I have, when plugged in, causes both fans to spin (to test them). The small one vibrates really bad, the large one is ok.

I let the car idle on a hot day 29c, for around 20mins, the engine temp was getting warm, I could see the heat waves from the side of the car, but the small fan never turned on.
I tried the AC, but that didn't turn it on either.

I'm thinking of getting a second large fan, and connecting the two of them so they both come on at the same time. Might improving cooling under the hood a bit.

Any thoughts?