Vacuum check valve location in 2004 Ford Explorer?

Question

My car has been having issues with the vents. First thing that happened was the air blowing out all the vents. After some searching of forums, I got that figured out and fixed. But now it's stuck on defrost. Turns out the vent flaps are controlled on a vacuum system, and that there are sometimes issues with the check valve. I believe this is the case for my car as well. I have no idea where to find it tho. Can someone help me out?

Answer 1

There are vacuum diagrams available for the hvac system allowing you to check the vacuum supply.

There is a large vacuum reservoir somewhere. Probably in the engine compartment that the engine is hooked to.. You should start there. One hose to it connects to the intake manifold. The other side hooks to the emission system and a single line into the cab for the hvac system.

A hand pumped brake bleeder kit is going to help. This allows you to use small long nose vice grips to squeeze rubber not the hard nylon sections of hose closed to test for leaks.

Answer 2

I had a friend that a similar issue where the air would only come out the defrost vents. If you open the glove compartment pull it completely down. If you look behind the main vents there is a control arm. The pin broke and the arm would move but not the vent which cause the vents to be stuck on his. With the car running turn on the ac look where I mentioned switch the vent control to defrost then main vents and you will see the arm move. See if it is attached and moving the vent open or closed. I rigged the arm back by sticking a shoelace through the hole and back to the vent control and it’s worked ever since. Hope it helps!