It does not know when you are going to shut off the engine, so it can't turn off the a/c ahead of time, but as long as the evaporator drain is not plugged there is no need to turn off the a/c before turning off the engine. By the same token whether the compressor is disengaged before the engine is shut off makes no difference as far as the system goes. The compressor will stop its work either way and the pressures will equalize through the expansion valve.

When starting the engine, the climate control will not allow the compressor to engage for a delay that allows oil pressure to build and stabilize.

The 124 Climate Control will last longer and be more effective if you just set the temperature that you like and forget about it, winter or summer. Leave the center button pressed and the auto fan button pressed.

Mine has been this way for 6 years and I have had to do nothing to the system whatsoever.

Good luck,