I have a 2009 Impala ss. When I turn on the AC, the passenger side fan turns on. The other day my car was running a bit hot. The temp gauge went up past the middle to 3/4ths. I get home, open my hood and the driver side fan is not working. I'm guessing both fans should be on if it gets that hot. Now if I don't turn the AC on, eventually the driver side fan will turn on when it needs to. So, both fans do work, but not at the same time. I'm not sure what the problem is.