I have checked both check valves on the passenger side of the intake and both have vacuum and it only goes one way, so from reading the threads I believe them to be good. The problem is I only have defrost. I use to have air coming from the vents but when I took the CV off and reinstalled them all I'm getting is defrost. Did I screw up the vacuum somewhere or is this another separate issue? I don't have Cruise Control. Thanks for the help!

 

Did you install the check valve backwards?

 

That is a possibility. When you blow into the CV it should allow air in one way and not allow air in the other end correct? I tried that before reinstalling, but I'll check it again.

 

Actually, you should suck on it...... (that sounds really disgusting......) install it such that the manifold can suck on everything else.....

I am going to go and take a shower now..........

 

HAHA!!!!!! I'll have the old lady test it then.... OK, now I'm going to the shower.

 

My truck does the same thing to an extent. It will only change the vents when I am on the throttle a little. Check valve works, maybe I've got a small vacuum leak?

 

When you say you don't have cruise control do you mean it doesn't work, or the truck just doesn't have that option?

Smashed-And-Ram, certainly a possibility, that would cause your symptoms, that vacuum system runs the vents, 4x4 cad, and the cruise, so check all those lines. When I had that issue it was because of the cruise, the vacuum line running from the cruise was so brittle it had just completely broke, I replaced the brittle part of the line and then it was good to go.

 

Make sure that they hold vacumm. The first time I checked mine they only let air go one way, but without holding vacuum I still had wild vents.

 

I should have clarified that. My truck doesn't have Cruise as an option. I think I'm going to go ahead and replace the CV with dealer parts anyway. Couldn't hurt anything now!