74 Charger blower works but no air from front window defroster

[74ChargerSE440]

So, the blower and air flow works fine accept there is no air coming through the front window defroster. I have to get it fixed for the inspection the 31st of January.
What could possibly cause this and how to fix? Does anyone have a clue?

 

[davek]

do you hear the door opening or closing when going to defrost to heat? cable not working?

 

[T2R9]

All the positions are controlled by vacuum so first ensure the main vacuum feed going to the control is connected. The switch will then open/close doors when in each position. This pic is the rear of the heater controls on my 74. The white check valve is the feed from the engine compartment which will go to manifold vacuum.

 

[dadsbee]

Move that lever to defrost...

..and if that don't work you're into the vacuum mess above! That said, you can probably get into the heater box by removing the cover and manually move (and jam there) the flapper to have heat and defrost to pass inspection.

 

[hanks73340]

As T2R9 stated, check your vacuum lines. Had same issue after rebuilding my Heater / ac box.

 

[74ChargerSE440]

Move that lever to defrost...

..and if that don't work you're into the vacuum mess above! That said, you can probably get into the heater box by removing the cover and manually move (and jam there) the flapper to have heat and defrost to pass inspection.

'Move the lever...'? Don't know what to think of that. Maybe you thought the position of the lever in the picture was the actual position we tested the defroster on .... (I alway post at least any picture because a start of a thread without a picture sucks).

Your second advise to manually move the lever I really do appreciate. I will pass it on to my mechanic in case he hadn't thought this out by himself yet...