Hey everyone. New here so i will do my best to state my issue clearly. I have a 99 chevy blazer 4.3 liter 2 wheel drive 370k miles. My AC only seems to be drawing from outside air. I figure it is one of the actuators but cant find anything definitive online. So i figured "Hey, why not ask the guys who have Blazers as well !!" I know 1 or more of the actuators is bad because it will not shift from vent to floor or to defrost. But hey, at 370k miles as long as the vents work i am fine with that. But with outside air, the vent output is limited. Re-circ air i hope will have more output. And i do not have a recirc air button on my system. I have read that the "MaxAC" fills that role. But AC or MaxAC has no difference in output. Thoughts??

 

The blend doors are vacuum-actuated. Make sure your vacuum hoses are good and you don't have any leaks.

 

Dityo on the vacuum hoses. They tend to rot and then leak.

 

Take a look at the actuators behind the glove box door; drop the door down and there are two actuators.
Also take a look at the two that are towards the center above the accelerator pedal. Check to see if the white plastic piece has broken.
There is also a "valve" that is inside the ducting called the defrost valve. Common for it to break. This is what shifts air flow from floor to dash. Search here, you will find pictures.