please help 1996 could this be true?
my 96 v6 does the same thing. vents all over the place. cant find any issues though. no leaks that i can see. im doign the plenum today, will keep an eye on it going forward and see if that fixes it
Hall Of Fame
Joined: Jul 2006
Posts: 12,204
Likes: 10
From: Gainesville, Ga.
^ when the plenum is done, replace the little check valve(s) on passenger side of the intake, in and around the firewall. also check vac lines for crack or break.
not sure about yours, but on my 01 there is also a vac canister under the cowl, with more vac lines in/out of it.
not sure about yours, but on my 01 there is also a vac canister under the cowl, with more vac lines in/out of it.
Champion
Joined: Feb 2009
Posts: 3,416
Likes: 4
From: Bay Area, CA
Mine does it. Anything over 75mph and it goes to defrost permanently until I slow back down. Whenever I put a load on it, or floor the pedal, it switches from whatever setting I have it on to defrost. I have a new Crate motor in it too. I got a friend with a 96 extended cab that does the same thing. Not sure if it is normal, but this mechanic isnt lying to you.
But Like Hey You said, I think I may have a BAD PLENUM.
But Like Hey You said, I think I may have a BAD PLENUM.
Last edited by J415; Aug 20, 2011 at 12:21 PM.
Professional
Joined: Jul 2011
Posts: 124
Likes: 0
lol. So someone mentioned this is a common vacuum leak. [the heater vents blowing out the defrost under load] Then how do you fix it? I love the reference to common problems without any reference to common solutions =] I am going to check and do my plenum too, I am pretty sure it is bad that and I need to remove a valve cover anyway to see whats clacking on the passenger side. I also have no vacuum canister. does a 96 5.9 have one? Would this be a cause of my vacuum problem assume nothing else were wrong?
Administrator
Joined: Apr 2010
Posts: 87,397
Likes: 4,213
From: Clayton MI
The common condition is known as "wild vents". I think there is a thread about just this problem in the faq section. Basically, eliminate all the vacuum leaks, and replace the check valves in the lines by the intake, on the passenger side.