A/C and heater not blowing out correct vents?

KADEWR

MEMBER
2002 CHEVROLET AVALANCHE
4WD
AUTOMATIC
200,000 MILES

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.

Wednesday, September 18th, 2024 AT 7:31 AM

1 Reply

JACOBANDNICKOLAS

MECHANIC
110,108 POSTS

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.

Images (Click to make bigger)