2000 Ford Windstar Knocking or bumping sound when heat is r

[quote:636f81c416="JimWindstar"]Heater problem
2000 Ford Windstar 6 cyl Front Wheel Drive Automatic 186000 miles

The A/C works with a knocking sound under the middle of the dash board.
When heat is requested, no heat but the knocking sound continues.[/quote:636f81c416]

i just had the problem fixed in my 2000 ford windstar..it is the actuator motor.. stripped gear.. however also common to the problem is the blend door.. being plastic.. frequently cracks and then flops.. i changed both.. i got an upgrade blend door all metal from heatertreater.net
mine was doing the same thing blowing cold and knocking noise..

Can you tell me approx. the cost to repair this and if you did it yourself? Email me at [email protected]. Mine is a 2002 with 88000 miles and the back heat works, but the front only blows cold air.

Thank you