My 2013 Prius will not go into defrost. The light comes on when the button is pressed so I don’t think it’s the Heat/AC controls. Does anyone one have a diagram of the Heat/AC vent system or have any ideas on what can be done to fix it.
The little electric motor control that moves the air between face feet defrost etc is not working or hunting and not working properly there are threads here about this in various and sundry models I think they're all about the same they won't all use the exact part though The thing you're looking for is usually attached to the box that houses the air conditioning evaporator the part that's inside the car and the heater core in my car it's a black almost square looking device that's attached right to the side of the air box assembly and it literally moves a lever through its turning arc to make the air come out of the proper vents whichever button is pushed usually something along those lines is getting messed up.
The device is actually right about where your gas pedal foot sits so looks slightly to the right of the gas pedal you'll see the white plastic evaporator case air box assembly and this black sub assembly attached to it with three silver screws of course there's probably a plug somewhere on it and all that I believe this is the device that moves the air to the given vents the right side of the air box would be where the passengers left foot would be but I didn't want to be confusing.