1991 Civic Si.. When I let my car idle for any length of time, it overheats, or almost does. As soon as I drive, it's fine. Obviously my fan isn't working, what is the logical way to test everything? Can I wire the fan directly to an circuit that's on with the ignition, or is there a better way to figure this out.... Thanks for the help

 

just unplug the plug on the fan and hook up wires directly to the battery, if it turns on it works. then test the line going to the fan switch . ground it (when the car is on)if the fan turn on its just a bad fan switch

 

It could also be the fan relay.