WTF, worked fine yesterday. today i went to my car and turned a/c on. it comes out of the defroster vent by the windshield even if i have it on bi-level. (it also does this with te heater and vent)

what is causing this? Or where should i start looking for the problem?

 

Sounds like it is in default mode which happens if you loose vacuum to the control head. I would first check the vacuum lines under the hood. You should have a vacuum canister (round ball looking thing) on the drivers side under the evap canister inside the fender wheel. vacuum runs from the intake manifold through a check valve then t's off to the vacuum canister and the vacuum lines that run through the firewall by the evaporator case to the control head. make sure there are no vacuum leaks through these lines and that they are all hooked up properly.

 

you're right, i looked today and it was a F'd up hose that plugged into the back of the intake (next to the dist.) got new hose and it fixed the problem.

thanx alot

 

No problem, glad i could help.

 

for the two vacuum lines that run inside the cab that "power" the vents and stuff, should there be a check vavle in there? does it have to go through the vacuum ball? or can I run it straight off the intake? thanks. lil jay

 

well the way it is suppose to work is go from the intake through a check valve and then tee's off from the back side of the check valve. one goes to the canister(ball) and then the other to the lines going to the cab. the reason for this is so that when you take off you wont loose all vacuum to the controller which keeps your vents blowing through the correct ones on acceleration. if you hook the lines coming from the cab directly to the intake it will work, but everytime you take off it will loose vacuum and will switch to defrost, then back again when you receive manifold vacuum again.

hope this helps.

 

putting the check valve in would eliminate this problem? thanks

 

well not really. the vacuum (ball) is there so that you have a supply of vacuum. rather than just the vacuum that was left in the lines. the vacuum left in the lines wouldnt be sufficient enough to keep the a/c through the correct vents.

 

ohhhhhhhhh. ok that makes sense. i dont have AC, and will only use defrost and vents, does this have any bearing on anything?

 

ok, maybe i made you think that it only matters with a/c, but in order to get your blower motor to blow through anything but the defrost mode you must have the vacuum hooked up properly.

 

cool man, i appreciate your help. :hail: