Interesting experiment for me. I purposely stalled the plane with A/P engaged. As Mark noted, A/P turned off. Here is where my anomaly kicks in. I have the A/P on/off tied to a button on my yoke. It does turn the A/P on and off as it should, except when it disengages from the stall. It will not turn off the A/P disengaged warning sound, nor will it re-engage the A/P, even after the stall is corrected. I have to use the keyboard command to silence the alarm, and only then can I re-engage with my yoke button.