I have a vaccuum leak and am looking for a diagram of the vaccuum lines. Where can I find one? Also, which vaccuum line would affect blower vents on the 03 expedition?

look for a vacuum leak around the pvc or an exhaust leak, if all seems ok check the o2 sensors

check this diagram.and locate the vaccum line.

check the emissions vacuum lines for leaks and look at the vaccuum reservoir that controls the ac system for leaks or crimped hosing..

the blower resistor only runs the lower blower speeds, it doesnt have anything to do with the where the air comes out. you will need to verify that the vent mode control is getting engine vaccuum. usually on the rf area under the hood, there should be a vaccuum line from the engine to the heater box. this line might be disconnected or rotted off.

LOOK FOR A VACUUM LEAK UNDER THE HOOD NEAR THE A.C DRYER THERE IS A BLACK PLASTIC VACUUM LINE THAT GOES INSIDE THE CAB ,IT SUPPLIES ENGINE VACUUM TO THE A/C CONTROLL. USUALLY FIND THIS LINE BROKEN OR DAMAGED BY RATS

HOPE THIS HELPS

There will be one under the hood of the car... it is going to be small and maybe somewhat hidden but there will be one under there.... If not more information will also be needed... What size motor does this car have

It sounds to me like your vent switch cable is either bound up, broken, came loose, or the vent switch motor is not working if its electrical. If its vaccuum assist, you have a vaccuum leak in you heating and cooling vac lines.

check the vaccuum routing on your selector for leak listen for small hissing sound at selector check vaccuum diaphram under hood for leag plastic line goes into firewall

U ARE LOSING VACUUM TO YOUR AC CONTROL HEAD.

On your vette I cant remember if it is vaccuum operated or manual cable but either way get a manual for the car that has a/c heat in it . You either have a vaccuum line that broke or a bad diaphram or a broke cable. I am almost sure its vaccuum but check that first then look at diagram and slowly work your way from the engine to inside car. you can also try to listen for it with the car running. if its a cable operated then look underdash for the blend door and follow the cable to the a/c control on the dash . one of the two. if you cant find a diagram google it. does the controls feel any different now when truning them ?