problem with defrost/AC

[z28fireman]

Has anyone had a problem where their selector switch for the A/C quit working? I switch it from defrost to floor to a/c and any other place, but it does not switch the air flow. I checked the hoses behind the selector and all are fine there. Is there a vacuum hose somewhere i could check?

Any ideas????

[2001NBMZ28]

With a vacuum leak the default mode blows air only to the windshield/floor vents - if that's what is going on check all the vacuum lines behind the intake manifold.

[z28fireman]

ok, thats what it is doing. it only blows defrost and floor. I'll have to see if i can get back there to look.

Thanks

[WS-6]

I have a 2000 t/a and it does the same thing. Did you get it fixed? if so what did you do?

[0rion]

I see this when people do intake swaps and forget to put the little vacuum line on the back or it falls off or something it'll cause this to happen.

[WS-6]

The car is stock and i felt behind the intake manifold and there is nothing unpluged. I 'd like to think i would hear the hiss if it was unpluged dont you.

[Ten5TireRacer]

Most times you won't hear it over the engine/belt sound?

[WS-6]

I checked today and all the vacuum lines are pluged in and there is nothing loose. I followed one line from the back of the intake to a tee of some sort by the computer under the hood passenger side which one goes into the firewall and one goes into a wire loom and to the front.The other line goes to a valve of some kind on the driver side. I checked behind the control pannel in the past and everything is in good shape. I will look into it more when it gets nice enough outside to drive it.

[LS2Tuner]

It is due to vacuum loss as others said. There is sometimes a one way check valve that goes bad also. I can't remember on the F body's.
If you take a hand vacuum pump and give the switch panel adequate vacuum I beat it will work fine.

[IronBird]

I had this same problem last year. Drove me NUTS!! Turned out to be a L-shaped vacuum check valve under the hood, near the rear of the passenger side valve cover. It somehow had cracked. Replaced it (very inexpensive even at the "stealership" parts dept.), and it's been fine since. I bet that's your problem!

[bigrondownhiller]

My tahoe had the same problem. I Found a diagram online of the cables that switch the vents and noticed one of them popped off.

[WS-6]

Awesome, I'll look into replacing the valve next.I appreciate all of your opinions they are very helpfull.

[99ls1taJohn]

I'm having problems with my head lights when i turn them off they are makin a buzzzing sound. and when i turn on my runnin lights my head lights pop up..any suggestions what might be wrong? is the head light moter goin out or is there a relay might of went bad???...

[WS-6]

Do you hear the noise only while they opening and closeing or does it continue afterwards as well? Is the noise comming from inside or outside the car? When you say running lights are you talking about park lights?

[Silver Streak]

My blower and rear defrost just stopped working all of a sudden.. fuses all look fine... grrrrr I can feel when I select the different positions.. and if its warm air or cold.. and I hear the "hiss" ing noise when I change the selections.. but no blower.

[WS-6]

Possibly a relay, otherwise I am not sure good luck.

[0rion]

I'm having problems with my head lights when i turn them off they are makin a buzzzing sound. and when i turn on my runnin lights my head lights pop up..any suggestions what might be wrong? is the head light moter goin out or is there a relay might of went bad???...

headlight gear is stripped.......headlight fix

[IronBird]

Yeah, I've been runnin' on the free 180 degree "fix" for over 2yrs now.

[99ls1taJohn]

Do you hear the noise only while they opening and closeing or does it continue afterwards as well? Is the noise comming from inside or outside the car? When you say running lights are you talking about park lights?

the parking lights.....can hear it bought inside and outside but louder outside...it dont make any noise when i open them just when i close them...

thanks everyone for your help any more suggestions would be great!

[IronBird]

headlight gear is stripped.......headlight fix

Dude....