generator fan wont run

[cmillsap]

(07-11-2013 15:03)al perna Wrote:  David , this issue must be related to the alternator or voltage regulator . I feel good about how to proceed . It is the fan not turning that has me stumped . any ideas on this issue I could work on would be appreciated .

Al,

I suspect you already know this but I will ask anyway.
Are you connected to shore power when you start the gen? If so, and you start the gen; you will still see 120V on your 2 volt meters. If the gen is not producing 120V, then the power transfer switch will not switch to the genny. IOW, it appears the genny is running and producing 120V but it is not. Why? Because the 120V is still coming from the shore power. So disconnect from shore power if you are connected before doing any troubleshooting.

So if the problem is that the fan does not start when the gen starts to produce 120V showing on your 2 volt meters over the entry door; then the voltage regulator is working properly. So your problem has to be somewhere between the voltage regulator output and the gen fan.
Either the fan motor is defective or you have an open 120V (David says it's 240V) circuit to the fan motor from the gen.

First, I would eliminate the possibility of a defective fan motor by using a volt meter to see if the fan motor is getting voltage. I am not near my bus and I don't remember if there is a seperate junction box in that bay that the fan motor leads (wire) run to or if they run to the control box that is used to start the genny. But there should be a place to check for 120V (240V)power going to the fan motor somewhere in that bay.

The alternator provides 12V to charge the gen battery among other things. It may also power a relay in the fan motor control circuit. This I am not sure about but if it does there should be a 12V fuse somewhere in that circuit. I have yet to find or see an electrical schematic for the genny but I'm sure there is one somewhere.