i already troubleshooted everything for the aux fan to kick on. everything is fine, that 50amp fuse was fine, the ecm to fan was fine, we used a snapon computer tool to manually turn it on and we used a power probe and multimeter to check for the hz. all of that checked out fine. coolant temp sensor on lower radiator hose is new too. outside temp sensor is new. anyway to fix the aux fan? or is it a must replace?