Hi there,
When i'm idling or going down hill a/c works fine, but when rpm is a little bit higher, air is blowing only from the feet vent (still cold air).
same thing happens with vent mode (not a/c), higher rpms shift the air to blow just to my feet.

any ideas? Thanks

 

Vacuum issue on blend door.....

 

Yep. Check for cracked vacuum lines, vacuum reservoir, check valve. You can use your mouth. You might have a vacuum diagram sticker somewhere under the hood.

 

If it's a 4.3, I can 99% guarantee the vacuum leak is where it taps the vacuum for the HVAC controls, right about center of the intake manifold. It goes bad often. I replaced it twice on my '00 Astro.

And FYI, air will always be present at your feet, regardless of the HVAC setting. But when you lose vacuum, the default is to go to defrost. Easily missed on a vehicle with a long dash.

 

Haha me too. I also had a '00 but I only had to replace the line once. It was made of hard plastic, and it was routed right over the hot engine, so of course it would get baked and brittle after time. Luckily the dealer wanted less than 10 bucks for a replacement.

 

My dealer gouges. It was $11.00.