I've got something backwards in my vent system....

[Mattchu60]

So I recently completed my restoration of a 87' C10. Out on the road testing and noticed the vents are "backwards".

When I put the air system to "vent" it pushes all the air to the floor ducts. When I switch to "heat" it pushes the air to the dash vents.

I'm pretty sure thats not right. I'm stumped on what I did wrong here. I did put a new heater core in so I had to remove some of the heater door parts, but I thought I got them back together correct...but maybe I didnt?

Anyone got an idea on this one? Could it be that the vaccum lines are backwards somewhere (I dont think so....only really can connect them in one spot).

[kglowacky]

my guess vaccum lines reversed or one is disconnected. Look under the glovebox see if you can see one hanging. One could have fallen off or broke when you removed the heater core. Check to see if one has a crack in it.

[Mattchu60]

I figured it out after taking the system apart. I forgot there are two vacuum lines that connect to that door system, I had the lines reversed. Switched them back and it works correct now!