Last night my A/C in my 2017 3 started blowing hot air. It’s coolish when the car is just running off the battery but hot when the engine kicks in. The battery is now fully unplugged to reset the system. Any other ideas on easy fixes for this. Also, when I disconnected the negative cable on the 12v battery the door lights and dash lights still come on so I disconnected both the positive and negative. Any clue why things stay on with the negative cable plugged in?
Have you got any trouble codes from the HVAC system? Generations after gen 1 give you HVAC codes via a scan tool. Up to gen 3 at least, there is also a way to get codes without a scan tool (scroll to the bottom of Blink (a/k/a Flash) Codes – How to. | PriusChat), but I don't specifically know how you do that in gen 4, if it's still supported. It's usually not too hard to answer an "is the blend door working" question by sticking your head down there and watching, while moving the temperature setting from below to above the cabin temp. It might help to find a diagram of the gen 4 HVAC box so you know where to look.
