After the car is started, there is a gurgling noise that sounds like when you are drinking from a straw and have reached the end of your drink. It could also be described as electric-motor like in the sense that it sounds like a servo being actuated repeatedly. I have not noticed any difference in vehicle operation other than hearing the noise. It sounds exactly like this: https://www.youtube.com/watch?v=hO2bjIel0yM "Kia Optima SX Dash Noise"
My car has 74300 miles.
My car has an automatic transmission.
I really liked your idea of including the youtube link of the sound you are hearing.
The sound is pretty subtle in the recording, but I think it is coming from the Mode Actuator or Temperature Actuator. Those components are installed on the evaporator case and move doors, or flaps, to direct airflow depending on where you set the temperature and vent controls. Sometimes they lose track of their proper position and have to be recalibrated.
There should be a procedure for this that is Kia-specific, and the dealer service department should be well aware of it. It is also possible that the plastic gears in one of those actuators has broken and needs to be replaced.
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