heater/ac switch will not run on 1,2 or 3?

2004 CHEVROLET SILVERADO
173,000 MILES • 4.3L • V6 • 2WD • AUTOMATIC
Avatar
RAHLO18
  • MEMBER
  • 1 POST
The control switch only runs on 4 & 5. Will not run on 1,2 or 3?
Sep 2, 2015 at 10:18 AM
Advertisement
Avatar
JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,236 POSTS
Most likely a bad blower motor resister. Check that first. Here is the location you should look for burn mark or signs of overheating on the resistor. If the resistor is okay I would replace the switch. Check out the images (below). Please let us know what happens.

Images (Click to enlarge)
Professional Diagram for 2CarPros Members
Click here to log in and view diagram.
Professional Diagram for 2CarPros Members
Click here to log in and view diagram.
Professional Diagram for 2CarPros Members
Click here to log in and view diagram.
Professional Diagram for 2CarPros Members
Click here to log in and view diagram.
Sep 2, 2015 at 12:20 PM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.