2005 Chevy Silverado mode valve

JAB1965

MEMBER
2005 CHEVROLET SILVERADO
V8
4WD
AUTOMATIC
80,000 MILES

My truck only blows air thru the defroster vent, and no other vents when selected. Hot or cold air both go thru the top of the dash. I was told it was probabley the mode valve actuator, and it is above the gas pedal, on the blower box assembly but I can't see it How do I change it, and do you know the part number, and where I can get it. I will also need pretty good instructions as I have never worked on a car with air bags before, but I am a pretty handy mechanic and have all basic hand tools.
Jerry

1 Reply

MERLIN2021

MECHANIC
17,250 POSTS

This is an auto temp control system? Try this first.
Alternate Method (w/o Scan Tool) 1. Clear all DTCs. 2. Place the ignition switch to the OFF position. 3. Install the HVAC actuator. 4. Connect all previously disconnected components. 5. Remove the HVAC/ECAS fuse for a minimum of 10 seconds. 6. Install the HVAC/ECAS fuse. 7. Start the vehicle. 8. Wait 40 seconds for the HVAC control module to self-calibrate. 9. Verify that no DTCs have set as current DTCs. IMPORTANT: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.
Disregard the install actuator, unless you actually do need to replace it, I recommend scanning for B and U codes, a good shop can do it for you, and this will save the expense of replacing good parts!