Have a 2004 Dodge Dakota Quadcab with the small V8. Started having heater blower issues about 8 years ago. Replaced the resistor at that time.
The system worked fine until last summer. Smelled burnt electrical and had no blower. The local shop replaced the blower motor, resistor block and stub harness. Replaced the motor at their suggestion.
Worked fine until 2 weeks ago. Again smelled burnt electrical. The blower stopped working AGAIN. The shop found the wiring harness burnt and resistor dead and replaced both. They said the motor was fine. Hmmmm
Now yesterday turned on AC and smelled slight burnt electrical ( been down this road before ). Turned off AC during the hottest day in ages. This sucks.

I am wondering what could be causing the resistor and harness to burn up. If they have replaced the motor last year, what else could be causing this?? So the 1 year old motor could be bad. What is the source of the parts China or Dodge OEM?? Not sure I what to replace any more parts until I understand better what is going on.

 

Could be high resistance in the ground circuit for the blower. (That assumes the switch provides ground path.....) That would tend to heat things up. Lack of airflow over the resistors would let them get excessively hot...... Too small in diameter wiring could also be a contributor.....