The driver side radiator cooling fan of the 2 fan assembly is completely not working. Only the passenger side one comes on, when AC is on or the car is in bumper-to-bumper traffic where there's limited air flow. That at least keeps the engine cool.

I did some troubleshooting. I had a few jump-starts. I know the 50a fuse on the positive terminal cable controls the cooling fan. So I replaced the battery and the entire battery cable assembly. The problem still exists.

Then I took out the whole fan assembly, and tested each fan motor. They're both spinning.

Haven't swap the relay in the engine fuse block yet, but it's a possibility.

So, what's my next step?

 

Check the relay