OK. There's certain things that will run after one parks the car. Some HVAC wind-down. When the A/C is running condensate (i.e., warm, humid air hits cold coils and one gets water droplets all over) drops out of the coil and drains onto the floor. So far, so good: But if one just turns off all the fans when the car gets parked, the coils are full of water. And random dirt that gets through the filters. Resulting in the famous, "Stinky feet" smell.
The preemptive strike that Tesla does these days is to turn off the refrigerant and blow air through the coil until it's (a) warm and (b) dry.
The other solution, as those of us who've had the cars since before the change, is to take off a fair amount of plastic on the right side of the front passenger's footwell, remove the air filters, and spray with an auto part store concoction that'll clean out the coil. That works, but it's not fun to do.
Second: The car has Sentry Mode which, I presume, you've enabled. That's fine for when one is parked on the street; but it you've got the car in a garage where, presumably, $RANDOM_PEOPLE can't get at it, you can set up Sentry to turn off in certain locations. Like, for example, the garage.
There's at least one other thing. Under the charging menu, there's a "scheduled departure" setting which, if set up correctly, will either get the A/C or the heating running (depending upon the time of the year, natch) before one is set to leave for work. Or come back from work. (It can be set up for location dependency). It's possible to set it up for random times, in which case the HVAC may start turning on at unexpected times. Check it?
Other than that, can't think of anything off-hand. What, specifically, are you seeing, beyond, "What is the car doing?"
