No air from vents

[pagrunt]

Pagrunt, (or anyone else) I have a question for you. I did the heater box mod as suggested in your post. Just waiting on a fresh heater core…

I am looking at the existing core/ductwork. I see that if the blend door is open to COLD, the door covers the core and directs air into the ductwork. However if the blend door is set to HOT, the ductwork is blocked off?? The other side of the core seems to just dead-end inside the box ????
What’s wrong here?

From the flow diagrams in my service manual it'll flow into what looks like a void/dead space but is where the floor & defrost feed off of for heating.

 

[Baker7888]

From the flow diagrams in my service manual it'll flow into what looks like a void/dead space but is where the floor & defrost feed off of for heating.

Ok thank you. There does happen to be a small square hole in that void space so that must be it.

So is heat only a function of floor and defrost or will it blow thru dash vents too?

 

[pagrunt]

Ok thank you. There does happen to be a small square hole in that void space so that must be it.

So is heat only a function of floor and defrost or will it blow thru dash vents too?

On heat you'll get 80% of the air flow to the floor & the other 20% to the defroster. On defrost it'll be the other way around. Vent will get simular 80% center vents/20% floor. System defult per how the Astro Ventilation functions is the floor & defrost vents has equal air floor when the function lever is OFF (kind of a safety feature incase somethimg isn't working on the vacuum side so there is some heat flowing, poorly, in the cold weather). Dash center vents only work when in VENT & all A/C modes. Outer vents are A/C modes only. Floor vents will be flowing regardless of the mode, just amount of flow depens on which mode is selected.

 

[Baker7888]

On heat you'll get 80% of the air flow to the floor & the other 20% to the defroster. On defrost it'll be the other way around. Vent will get simular 80% center vents/20% floor. System defult per how the Astro Ventilation functions is the floor & defrost vents has equal air floor when the function lever is OFF (kind of a safety feature incase somethimg isn't working on the vacuum side so there is some heat flowing, poorly, in the cold weather). Dash center vents only work when in VENT & all A/C modes. Outer vents are A/C modes only. Floor vents will be flowing regardless of the mode, just amount of flow depens on which mode is selected.

Thank you. Heat works mint now