A/C and heater not blowing out correct vents?

2002 CHEVROLET AVALANCHE
200,000 MILES • 4WD • AUTOMATIC
Avatar
KADEWR
  • MEMBER
  • 1 POST
The A/C and heater will blow out the defrost vent regardless of what I set for it to blow out of and automatically alternates to blowing out the main vents and it continuously alternates between the vents, swapping about every 10-20 seconds. The only exception is that about every 2-3 weeks It will only blow out the main vents but only blows at about 1/4 of the max regardless of how high or low I set it to blow, then after about 2-3 days it goes back to alternating between vents.
Sep 18, 2024 at 7:31 AM
Advertisement
Avatar
JACOBANDNICKOLAS
  • ASE Certified Mechanic
  • 110,194 POSTS
  • ASE Certified Mechanic
Hi,

The mode door actuator is responsible for the air flow direction. Chances are it has failed or is failing.

First, take a look through this link to see if anything is helpful:

https://www.2carpros.com/articles/air-vents-stay-in-the-defrost-position

Next, I have attached pictures below showing the actuator location and the directions for replacement. Note that this if for a manual climate control system. If you have automatic climate control, let me know.

Also, I placed the letter I in one pic and highlighted it. That is the start of the installation process. The very last picture provides the recalibration procedures.

Let me know if this helps or if you have other questions.

Take care,

Joe

See pics below. Note: The arrow in the picture's points toward the front of the vehicle.
Sep 18, 2024 at 6:31 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.