98HAVACTA

iTrader: (1)

Hey guys,
Just registered to the site, and was wondering if ya'll could give me some help with my a/c. I've been wanting to get it recharged after my compressor went out but i first want to fix the vent problem i have. Have any of you experienced this when you vent dont want to blow air threw the a/c vents it just blows air threw the defrost vent down at the bottom and windshield. I've changed the control panel but nothing yet, i even got vaccum as far as the engine compartment dont know of anyother place to check. Any advice?

GOaT Cheese

Need to know year make and model.

UCFWS6

iTrader: (4)

maybe the hose that directs the air to the vents fell off into the dash. is that possible? had it happen on a diff car before but not an ls1

2001NBMZ28

Believe that's the "default" mode - look at all the vacuum lines behind the intake and going back towards the passenger side.

DBUS6

iTrader: (6)

^^ What he said (2001NBMZ28).
Look under the hood w/engine running and listen for a vacuum leak "HIISSSing"
Maybe a loose line or what I had, a bad (broken) check/T valve.
Good luck!

98HAVACTA

iTrader: (1)

I have a 98 TA, I do get vaccum to the motor compartment but i cant get any change in the inside of the car i really dont know where or what could be causing this problem under the dash

ghardester

You changed the control switch on the dash? It's also run by little vacuum tubes. Start the car then go to the drivers side and put your head down by the switch. You should be able to hear the hiss when you move the switch positions and vents opening and closing. I have chnaged that unit and the first time I didn't get it right. Just a thought.

GOaT Cheese

Have you changed or messed with the intake or MAP sensor? The vacuum source for the interior is a small black plastic line that "T's" in at the MAP sensor vacuum connector. If you look at the firewall you will see a large black wiring loom conduit, the vacuum line breaks out of the conduit right around the rear of the R.H. valve cover, it only sticks out about 3 inches before it connects to the MAP sensor vacuum connector fitting. The vacuum line is easily pulled out of the MAP sensor fitting, I've done it a hundred times, and there is very little slack to pull, it can be tricky getting it back where it belongs. Anyway, check that.

98HAVACTA

iTrader: (1)

I checked every thing but nothing yet do you think it could be a bad compressor that stops it from working and what exactly is default mode? Is that when your a/c doesnt have freon and it stops working right because of the pressure switch?

GOaT Cheese

The interior mode doors have nothing to do with the compressor. If it only blows out the bottom vents, then it is a mode door problem of some sort. Either vacuum to the control head, or an actuator problem, etc..

98HAVACTA

iTrader: (1)

Still alittle lost, (interior mode doors)?

GOaT Cheese

There are to sets of "flapper" doors attached to the evaporator case under the dash. The mode doors (two with dual zone a/c) control where the air comes out, at you feet, or dash, or both. The blend, or mixer doors control the temperature. I believe that on your car the blend doors are controled by electric stepper motors, but the mode doors are vacuum actuators. If the air is only coming out of the floor vents, then you have a problem with the mode doors, if you can control the temperature normally, then the blend doors are okay. You say you replaced the control head, do you remember attaching the clear round plastic vacuum block the back of it, and all the red and blue hoses looked okay? With the engine running, do you have manifold vacuum at one of those lines inside the car?

98HAVACTA

iTrader: (1)

I have vacuum you are right the blend door do work because if i change the temperature it does work so do the speed of the air comes out works too. But nothing yet how do i get in there to change this actuators or check the hoses?

98HAVACTA

iTrader: (1)

Hey guys thanks for the information i finally got it you were right it was one of the mode doors that was bad. Thanks.

Dan

iTrader: (1)

Mine has been doing the same thing for a couple years now..I went out today & played with it & noticed the tube wasn't hooked up on the very back of the intake(under the plug) I plugged it back on & that still didn't work, I did notice that the plug doesn't fit on very well. I don't know if the SLP unit has a smaller diameter fitting? It is not in there very tight & will probably slip off.