I have 1999 blazer and the ac blows ok. When i press the recirculation button nothing happens. It use to work just fine you could tell when it changes over, now nothing.
I checked all the fuses and they are fine. Just don't get it. Any ideas?

 

The recirc door is vacuum actuated. You can see the actuator by dropping the glove box down out of the way. Open you glovebox and empty its contents. Look up in the left corner of the glove box for the catch. Pull back on the catch and rotate the glovebox door down and out of the way. The large plastic opening with a vacuum actuator in the middle of it is the recirculation door/grill. When you press the recirc button, you should have vacuum to this actuator. If you do not, then the problem could be in your control module. If you do, then the actuator is bad.