So I've searched and read most every thread I could find regarding "heat", "no heat", "poor heat", etc. and posted in most of them but I can't seem to find anything that addresses the specific issue I'm having....forgive me if I've missed it

My vent selector works, not 100% (when I accelerate it defaults to defrost) but it does change from vent to vent under normal driving conditions but the problem I'm experiencing is when I move it to defrost and adjust the fan to high I hear a lot of air blowing around behind the dash and it seems like it should be working but when I put my hand over the defrost vent hardly anything is coming out....does this sound like the usual vacuum issue or is there something else? It's also pretty weak on the floor but blows the best from the dash vents.

I've traced the lines from the vaccum reservoir behind the bumper to the firewall and from the intake to the firewall and they all seem to be intact. I'm wondering if it could be a vacuum line problem between the firewall and the selector or venting mechanism, is this possible?

 

It is a vacuum leak somewhere, just have to find it, or it could be that the vacuum canister is missing, busted, or unplugged (which is a vacuum leak).

 

That's what I've been thinking I just can't seem to find it. The canister is there and doesn't seem to be busted/cracked and the line is still attached....I'm just going to have to keep searching I guess. Could something be broken behind the dash that directs the air flow from vent to vent?

 

Sure hope you find your problem. Mine is doing the same thing and I have no vacum leak anywhere and believe me I checked.

 

Me too! On top of that my heat is barely warm...and that's after multiple flushes with CLR and verifying that my blend door is still functional, what gives?!

 

Check the vacuum reservoir itself for cracks or holes. Check it with carb cleaner.

 

I use ether to find vacuum leaks, if a line is busted under he dash or what not thats still a leak.

EDIT: Check the vacuum check valves, both of them. You should be able to suck through them one way only, if one is bad I would replace both, they make sure that you have vacuum when the engine doesn't, i've seen a few fail. They are in the vacuum lines under the hood.

 

That would be my first thought. The canister may be leaking (spray it with carb cleaner) or possibly the line is collapsing...Tj