My top fan was not working as well and it's not cooling either. While unit was unplugged, I discovered taking the top panel off of the LED display reveals the circuit board. In there on the left side are 3 plugs which go to the 3 fans. They are color coded: Red, Yellow, & White. I swapped the the Yellow & White. Top fan works now, but middle does not. Try that just to verify the fan works. I'm still trying to find out why it's not cooling.