I have a 1997 B3500 Van , 5.2L
No matter what I select I cannot get the air to blow on the floor ,
It blows only as defrost mode,,
I'm an someone please give me some steps or things to check as it's FREEZING in the NE and we have a trip coming up in 2 days ,,
Thank you

 

Vacuum hose from intake manifold to climate control unit not hooked up or leaking. No vacuum means default to defrost only.

 

Can you please tell me where that attachment might be, the location of those hoses where I can look, do I have to remove the engine cover shroud, or is it under the hood from the front? Or even perhaps inside the cab??

 

The post is correct in that you most likely have a vacuum leak, however it may not be directly the hose to the intake. Have you done any work in the dash or engine area recently? That most commonly what happens, you accidently knock a fitting out. However the port for the vacuum accessory circuit i believe is drivers side of the intake keg below the throttle body.

Does your cruise work? could quite possibly indicate the vacuum circuit is ok and you have a different issue.

 

You have to remove the engine cover, then the air cleaner assembly. From there, look on the passenger side of the intake manifold, about halfway back on the side of the intake will be a fitting with a vacuum hose, that's the one that drives the HVAC controls. From the intake it runs to the vacuum reservoir located under the passenger headlight.

The red arrow is pointing to the fitting.

 

Cruise works fine.
I did not do any work recently,,,
I did find the 4 vacuum hoses,,,, they look ok ,,
UPDATE
When I click it from defrost to buy level now I get air blowing out of the center vents and air blowing out of the top on defrost but still nothing on the bottom, I'm not sure what I did to achieve that, perhaps I didn't notice that it would work in that position, but just to be clear the only thing not working now is trying to get it to blow out on your feet,
Again cruise control works and this vent system does work partially

 

I replaced the check valve underneath the radio coming from climate controls to fix mine, was all gunked up.

 

Did you have to pull the radio out or could you reach up underneath from behind where the gas pedal is

 

Nope just took off doghouse to access all of such stuff.