Hello, I will do my best to help answer your General Motors Vehicle questions.
The noise you hear is most like one of your HVAC actuators resetting back to its rest or nominal position. The clicking you hear is generally heard when one of the actuators begins to go bad and the gears begin to strip. You must find which one makes the noise and replace as required. Once it is replaced you must disconnect your battery for 30 minutes minimum and allow the system to relearn the positions of the doors. It is important during the relearn do not disturb any controls inside the car for 5 minutes.