i have a 2001 blazer 4d LT with auto climate controls and i'm having air blow out all my vents regardless of what setting its on. i can hear a click when I change the setting but its not making any difference. anyone know what could be wrong.

 

The first thing to check are the under-hood vacuum hoses.

This tend to start failing at about 15 y.o. This loss of vacuum will also prevent the front axle to engage in 4x4 mode. These hoses can visually look ok but they can leak along cracks or where they attach to the fixed fittings.

The trickiest part is connecting to the vacuum reservoir that is hidden in the fender.

Check out the thread on this in my signature. The details of the hose routing will differ depending on if you have the 3-button or 4-button transfer case. The 4-button one is the one with the Auto 4wd option.

I'll turn this into a "sticky" thread.

 

i do have the 4 button/auto 4wd and it has no problem changing but i did notice the vacuum lines are very bad. ill try replacing some of them and see if it helps

 

The think about the vacuum lines and thw 4wd is that if you select 4wd, the transfer case will switch over and the indicator lights will change, but the right side half-shaft of the front axle will not have engaged with the differential. This is the insidious/annoying way this system fails. Everything will look fine but you won't have 4wd!

Be sure to report back if reparing the vacuum linrs helps.

Good Luck!

 

just got done replacing the vacuum lines and the only thing that changed is the face vents blow harder but the rest all blow the same as before. the face vents seem to get most of the air no mater what setting its on like it started to change but got stuck..

 

Hmmm, it must be something in addition to the vacuum lines.

I have the gm service manual but I'm traveling at the moment. I can post the diagnosis table in a few days. DM me on Wed. and I'll see what I can post.

Off the top of my head, I would guess it might bectge control module in the dash.

Perhaps someone else has an idea to suggest.

 

The plastic piece that connects to the vent door is broke from the vacuum actuator behind the glove box. The actuator works and moves when changing my vent selection but have no clue what that plastic selector is called or where to get it. It does move by hand

 

I found this site to have the best exploded parts diagrams.

https/nemigaparts.com/cat_spares/epc/chevrolet/54s-t/08/

Once I identify the part number, I check that it is correct for my vehicle by entering it in at an online gm parts seller that allows me to input my VIN.

I hope this helps.

 

i also just found one of the 2 actuators behind the center console is leaking vacuum slightly but are still moving properly.