recirculating mode behavior makes me think it’s a mode actuator
Not sure if this can help narrow it down, but I just checked my 07, by observing the intake door (drum) that controls where the air comes in from, i.e., outside, or inside recirculation. It can be watched by opening the glove compartment, and removing the cubby for the owners manual at the top. Look inside, above the cabin air filter location, for the white, sort of corrogated, horizontal, drum-like assembly.
(Note, I did not have to start the engine for the following.) With the ignition and blower fan on, and the mode switch not in one of the two windshield defrost positions, if the RECIRC is then turned on, the light in the RECIRC switch will come on first, and then 2-3 seconds later the drum will rotate to close off the external intake path and open the intake to the area under the dash. If the mode switch is then turned to either of the two windshied defrost positions, the RECIRC light goes out immediately, but there’s the same 2-3 seconds before the drum begins to turn. The same lag appears when the mode switch is moved back out of the defrost position, with the RECIRC light coming on but the drum movement somewhat delayed.
Both the intake door (drum) actuator and the mode actuator can be viewed this way as well. This provides a way to verify if the mode position is changing for each of the five positions, and the recirc actuator’s responses. (It will start operating before the drum visibly starts to rotate.
