A/C vent weak. changes recycl on its own

This is driving me nukking futs. I hear about the 2002 Envoy having a weak blower system, however, this is not true. The issue is it changes from vents to the floor and then back to the vents on its own every few minutes while the AC is on. I can hear it doing it. When it comes full force out of the vents then it is blowing fantastic until it starts to get quite again then becomes weak. It is almost like it is getting confused when the recycle button is pushed, however, it does it on all modes. Any clue on how to fix this? I have a feeling it may be the hydrolic vent system and the vent doors not closing like they should.
Thanks for letting me vent. (no pun intended)

you can email me on this.

My girlfriend just got a 03 SLT wtih only 15,xxx miles and it does the same thing. It has the automatic climate control. I wondered if this was normal or something common?

My girlfriend just got a 03 SLT wtih only 15,xxx miles and it does the same thing. It has the automatic climate control. I wondered if this was normal or something common?

The entire time this went on the temp was set at 60 which basically disabled the automatic function. I may have fixed the problem. I was sitting idle in the hot sun and began playing with the buttons. I pushed the defrost button to send all the air to the windshield. I heard a thump. Now it blows hard through the main vents. I am guessing the flapper doors under the dash may have been stuck or not closing all the way and by hitting the defrost button it seems to have "unjammed" the doors. I hope this helps others!!
Buzz

I'll give that a shot tomorrow.