Originally Posted by upallnight

The fan connector consist of three wires. Two heavy duty wires for power, 1 positive and the other for negative and a third smaller gauge wire which is the control to turn the fan on and adjust the speed of the fan. A pulse width modulated signal is sent on this wire to the electronic built into the fan. This signal is sent by the DME.

I wouldn't be advising people to use any type of untried testing method to see if the fan can be activated because you can go from an expensive fix to a very expensive fix if you ruin the DME.

To determine if the fan is the problem, the best and safe way is to get it scanned. A bad fan will post a DTC in the DME since the DME issues a command at the start of the key on cycle and if it doesn't receive the correct signal from the fan it will log a DTC for the fan. Even if the fuse is not blown, the fan could still be the problem. I scanned Babyduke X last summer and told him that the fan needed to be replaced if he wanted the ac to work. The fuse was still good and there was sufficient refrigerant in the system.