I have a 98 chevy truck. The fan blower switch only works on high. Any ideas on what may be malfunctioning or what needs to be replaced? A couple of years ago I put a different radio in the dash and am wondering if I may have damaged the blower switch or wire assembly leading to it. The blower switch continued to work after I put the new radio in for at least a year.

 

it could very well be the resistor, but that wasn't so in my case. i have a 97 sierra and the problem was a melted wire harness behind the blower control dial. the clip that goes to the wiring harness and the clip that plugs into the back of the blower control dial were both melted. this is a common problem from what i've heard. I went to a wrecker and got both pieces from a write off that weren't melted and installed them today, blower works on all speeds ... for now.

 

Probably is the blower motor, you can get a new one fairly cheap from http://www.gmpartsclub.com/chevy-silverado-parts.html Its a pretty simple fix to do yourself.