First, taking the clam off is not rocket science, and makes all the other stuff easier, or possible at all.
Removing the recirc covers is just required for the AC to work properly, and when it is all working properly a cool breeze is solved by turning the heat on, as the fan on low will easily overpower the breeze coming in.
To troubleshoot the temp flap, get a DVM
there are 3 wires on the connector for the flap under the access panels. Ground, 12 volts switched and 0-12 volts from the knob. The wiring diagram will tell you which wire is which. Disconnect the plug going to the flap servo. So with the key on you should have 12 volts across two of the pins, and a variable voltage on the third. If you have the 12 volts and ground check the third and see if it gives you a voltage that will vary with the knob. If all that is true, the motor is either dead or stuck. We have seen at least one member have a rock get stuck in the flap. Other than that, I don't know that you can get the servo out with the heater box in place, which means, clam off.
If you do not have these voltages, then the problem is up the way a bit. Pull the heater control panel out and look for stray wires. Since the recirc button appears not to do anything, it is possible the fan switch is not putting out the 'fan on' voltage that tells the switch pack module what is going on, but then your AC compressor would probably not fire.....
Have you done your heater resistors yet? If not, this is the time.