I have a 1999 lx470 and my rear heat will not get hot. when you slide the rear heat controller to hot it will never get warm, it always blows cold air. I really need this working. it gets cold in the very back seat for the kids. I pulled out the overhead rear control unit , thinking it might have a cable attached to it going to a damper to control the hot and cold but the unit is all electronic and has only wires. I do not have a repair manual. Maybe some one can help. Thanks for your time!