I'm having a hard time making sense of your post, so I will ask a couple of questions to help clarify things for me.
I gather that this problem has been occurring since you purchased this car, is this so?
I gather that you found a wire attached to the aux fan relay, is this wire something someone added or is it factory? If it's factory it will be in a harness with other wires.
Does the red switch on the drier have 2 wires made onto it and are they both plugged into wires coming from the main harness?
Does your A/C work? Blow cold air? If it does, the switch in the drier works on high side pressure of the A/C system. Without A/C gauges and knowing how to use them, it would be hard to explain how to test this switch.
Let me know the answers to these questions and we'll work on it some more.