i am working on a 2000 3500 van. it keeps burning up the hearer resistor. i put one in yesterday, made 2 trips, 10 miles each, and it was working fine . left out this morning and only had high speed again.what can be taking out these resistors? i had used aftermarket and oem and keep burning them out.

 

Might be the blower motor itself is old worn and drawing too much current. Check all the connections in the circuit, and the contacts on the low medium high switch. I've had to clean the contacts on my switch numerous times.