I hardly ever run my AC but had it on the other day and noticed a strange problem. With the fan on high speed it blows hard then drops off then resumes blowing hard. Completely independant of engine speed or if I was driving or stopped. While feeling around behind the fan speed knob I found the wires very hot to the touch after only about 5 minutes of operation so I shut it off right away since I don't carry a fire extingisher

It's the under dash blower unit installed in early cars.

Seems like an issue with the fan motor itself or an electrical problem. I was wondering if anyone has had this problem and how to fix it?

Thanks