This was the culprit!

[crawdad]

A few weeks back I had posted about a problem I was having with my defroster not working. Only place air would come out was the bottom vent. Also my A/C wasn't working. I had tried to determine the problem off and on over the next few weeks, but never could figure it out. This morning I went out and started tracing vacuum lines. I knew I wasn't getting any vacuum to the vacuum pod underneath the dash that controls the vents. Anyway I wound up pulling this check valve off and looking it over. Of course you can't really tell just by looking at it, so I went to the chevy dealer and got another one. Slipped it in and whala! Defroster is now working like a champ. Not only that but so is the A/C. But wait....there's more! My cruise control which had also been on the blink is now working like a new one. All of this for only $6.00 I'm posting this just in case any others out there ever have a problem like this. A good indicator that it is the check valve is if the vent system in the duct work quits working, A/C quits working, and cruise control quits working. This little check valve will cause all three of those things to happen. This check valve is located right near the distributor and it draws vacuum from the rear manifold vacuum port. Hope this helps somebody out sometime.