I had my 1500 2001 Express cargo fan on max to warm up the van. When I went to turn down the fan, I noticed that it was either on or off. The fan lo, 1 and 2 didn't do anything. what troubleshooting do I need to perform to see what is wrong? Is there a simple cure for this or does it get complex?

 

Most of the time I have experienced the switch being bad. The only test I can imagine is to see if the fan is getting power when on those other settings. If there is power, then the fan may be bad.

 

I'd put $100 on it being the blower motor resistor.....when the switch is set to high, it by-passes the resistor and applies straight battery voltage to the fan, which is why your high setting stil works. it can be found bolted to the blower motor housing

 

I agree with shawnvw on the blower motor resistor. They should give you the new style resistor when you purchase a new one. The new style won't/shouldn't burn up like the old one does. You will have to do a little cutting on the blower motor housing (plastic)to get the new one in... they give you a template to use to make it easier. I have done a bunch of these and it sounds exactly like what you are talking about.
Good luck

 

Shawnvw and stwdogg, your both right. I appreciate the advice. Modified the housing and changed the resister. Local shops where asking for big bucks to check and change. Wow, two bolts and an electrical connector. Thanks guys.

 

My Trailblazer's fan control only works on the 4 position. Could this also be the blower motor resistor?

Thanks

 

could be....what year? what speed isn't working?