MackJohn

Thank you so much for your replys...However, the problem is not that the fan is not working at all, but that it will not shut off and has a high pitch scream which can drive you crazy by the end of the day!!! What I would like to do is be able to put the fan on a toggle switch. That way, when the fan doesn't need to be on I can shut it off. This is why I was wondering about what the five wires do...any help or suggestions would be greatly appreciated!!!

I have a 2005 Mack Model 542 CXN613 with a Mack AC-427 Aset Engine. How does the electric fan drive function? What do the five wires that come out of the fan hub do? The fan is a Behr Fan. Also, has anyone dealt with any problems with the fan not shutting off? Thanks.