please tell me wher under the dashboard does the vacuum motor Oart # YH-1665 mou

Not sure of the part # you speak of,but are you chasing the blend door motor/actuator? if so it sits on the passenger side of dash and you will have to loosen the dash board and tilt in down so you can get a visual on it. Let us know and we can go further with instructions.

I agree with #1, tell us what is not wroking properly, heat or where the air comes out?