Defrost problems. Cost of pulling dash, repair/replace air dist box? on 2000 Ford Taurus

Defrost for front / side windows doesn't work well. Fan blow speed also variates according to car speed. (AC works fine). Told it was blower door, obstruction in mix box. Solution pull dash, repair /replace mixing box = $1,000. bucks.

Asked by for the 2000 Ford Taurus
it pays around 7-8 hours of labor plus parts. it sounds about right.