Hello all, My question is that ever since I've had the injectors changed, my blend door only allows air to come out of the defroster. I'm told that this is controlled by vacuum. Where should I start to look and where is that on the truck? Thanks for any and all assistance.

 

On my 97 there was a white vacuum line by the passenger hood hinge that was cracked. Cut out the bad spot and used heat shrink to connect the two. Works perfect now

 

The vacuum pump is on the passenger side fender under the hood. Check all the vacuum lines in that area for being unhooked or for any with cracks in them. Most likely the shop that changed your injectors forgot to plug one back in.

And yes, if your system looses vacuum pressure, the vents automatically revert to defrost only.

 

Be nice to know what year, engine etc...