I had the motor off the other day and could hear the blower motor for the heater is only on when the fan speed is on high. Does anyone know what area I should look at for this? Will this be a problem with the blower motor or the fan speed switch?

 

I just fixed this problem on my 93 by changing the blower motor resistor.

It was a real pain to unplug since the plastic on mine was kind of melted to the plug..lol

Google pic:

 

Yep.. you have the classic blower motor resistor problem, sometimes the resistor pack is burnt out but other times corrosion on the connectors is the problem.