Heater blower Electrical question.

Ok, Im summoning the almight XJ electrical Guru's. Last winter, I had a small fire under the dash at the pasengers feet. It appears that the reistor inside the blower box got so hot that it melted the plastic and caught fire. I assume that it may be a wire under the dash causing this problem. The only thing I have done electrical/dash wise was swap in a steering column from an 88. When I did this, I had lost power to the radion, HVAC controls and such. Found the supply wire and put it on a swith, thus providing power back to those areas that didnt have it after the swap. My question is, if I swap in a new box that is located there in the passenger footwell, how could I bypass the dash blower speed control? I have tried to locate any wiring that looks like it may have caused this problem, but to no avail. Winter is fast approaching and some heat would be nice!

1990 XJ Laredo, I6 - 312,000

No takers?

im thinking you could run power directly to the motor but youd only have high speed and if you wire in a switch use a relay too as its way too much amperage for a switch to handle

I was thinking I could use a variable speed controller