My heater motor only works on high - 2006 Chevrolet Colorado

Check the resistor bank connection first,I replaced two banks for the same reason . Check the resistor bank connection first,I replaced two banks for the same reason .

I had this exact problem with my 2006 Colorado. I was told the resistor was bad and needed replaced at $75. My son found that if he pushed up on something with his left foot under the dash the blower would come on. I since sold the truck but hope this leads you to a fix. Something under the dash is loose, placing upward pressure allows it to start again. This is obviously not a complete fix but should point you in the right direction. Good Luck P.S. Frames are thin, clean off any scale and coat with 2 coats of POR-15 or other frame protestant if you live in the snow belt states. Watch frame area below front of front door. Didn't catch mine in time. I had this exact problem with my 2006 Colorado. I was told the resistor was bad and needed replaced at $75. My son found that if he pushed up on something with his left foot under the dash the blower would come on. I since sold the truck but hope this leads you to a fix. Something under the dash is loose, placing upward pressure allows it to start again. This is obviously not a complete fix but should point you in the right direction. Good Luck P.S. Frames are thin, clean off any scale and coat with 2 coats of POR-15 or other frame protestant if you live in the snow belt states. Watch frame area below front of front door. Didn't catch mine in time.