I initially had the problem of the cruise control fading out and the ac blowing out of the defrost when the engine was under load. I tried finding the leak (it turned out to be in the cruise control servo, replaced that) and in the process removed the check valve on the brake valve. The check valve is still good, but I can't seem to get it to seal back in the brake booster. After I shut down the engine I can hear some air escaping the brake booster (I'm assuming from the loose check valve.)

Also, now upon start up I get a little bit of idle flux for a few seconds then I can hear the blend door close and the idle smooths out. I'm guessing it takes a few seconds for the vacuum to seal and build, that didn't happen before I messed with the check valve.

Any suggestions on how to seal around the check valve on the brake booster?

 

I used a Loctite product called Vinyl, Fabric & Plastic Flexible Adhesive. Seems to have worked because the check valve sealed up pretty good. Got it from Lowes but I think the other big box stores have it as well.

Applied it to the sealing edge of the rubber grommet, pushed the grommet into the booster, then let it set for two hours before putting the check valve in. I put liquid dish soap around the part of the check valve that goes into the grommet so it would slide in without twisting the grommet.

 

Thank you.

I'm guessing the other vacuum operated door might be the one that directs which vent the air is going to come out of.

 

Try it again with the mode selector in off (O). This will isolate the vacuum operated doors. If the problems still exists, the leak is between the mode selector and the intake manifold.