my 66 Mustang Blower Motor is week . Its a new 3 speed unit .all speeds work but don't feel any air in defrost. Replaced Ducts and cables. do i need a stronger Blower?
Halloween,
It sounds like an air distribution problem you have for defrost
You will need to double check your cables and ducts work
You may have a plugged up air intake of heater core (the weak? new blower motor)
Pull the blower motor back out and inspect for debris
Blow compressed air back thru the heater core from inside the case
Watch for dust and crap exiting the cowl panel vents behind the hood
Clean that all out real good and retest
+1 for seeing what is in the heater box.
I had a Cougar that stopped putting out heated air. Somehow the core was blocked with yellow fiberglass insulation. The sir box was nearly stuffed. I found No mouse droppings, and it was parked inside at night. It was a mystery.