You won't like it, but it seems to explain what is happening. The battery has to have at least 3/4 charge before it will work. Of course, as I told the Toyota tech that informed me of this fact, that makes it almost useless, as if a person drives over 5 miles from the last charge the battery will probably have less than 3/4 charge.
kinda surprising, considering pip has it with less than half the battery. you'd think the charge threshold would be lower.
Ask 'em to show you in writing. A limitation like this should also be in the owners manual. I had remote A/C in my Gen 3, which has a tiny battery in comparison to any plug-in, and didn't have this limitation.
I know I've used it with less than 3/4 charge. I remember reading something a few months ago about it not working if the doors or unlocked and maybe under some other conditions.
I'm guessing they don't want a Prime to run the heat pump unattended with the hood open - nothing to do with an engine bay light (I don't think there is one) Why stop there? There's a sensor on the fuel filler door and the charging port cover too, even on the base (Plus) model where the charging port cover doesn't lock (and there is an LED "flashlight" in the charging port area, by the way)...
yes, pip has those too, but no hood open detector. i guess they don't want you driving with the port open, but the hood up is okay.
Since writing this post, I have been able to run the A/C with much less than 3/4 charge, so Toyota was wrong.