Got 2001 chevy lumina and didn't have this problem never before.
When turn the a/c and/or heat, the air is blowing only trough windshield and under, no other setting will work.

The a/c is working fine, just can't turn to work properly.
The knob is working fine and turn to any setting, but the air is blowing only up and down.


Any idea???

Mine is the same exept once in a while (every month or so) the vent selection will work fine but 99% of the time, its stuck on defrost/floor. What would be the best stepts to take when diagnosing the problem.

There is a hard plastic vacuum line that runs from the engine, down around by the battery, then to the interior of the car that supplies vacuum to the HVAC system mode actuators. I would bet this line is cracked/split or disconnected. When it's bad, the HVAC will default to 1/2 floor and 1/2 defrost mode.

There is a hard plastic vacuum line that runs from the engine, down around by the battery, then to the interior of the car that supplies vacuum to the HVAC system mode actuators. I would bet this line is cracked/split or disconnected. When it's bad, the HVAC will default to 1/2 floor and 1/2 defrost mode.


I was not able to find this line.
Do you have a diagram how that line looks like???
Or the exact place where should I look at???

That would help me a lot.

Thanks for your advice and help.


Very sincerely,

Dino K

The vacuum ball resevoir is hard to find, it's buried in the area around the battery/washer fluid resevoir...you may have to move some stuff to access it. Once you find it though, you'll have no problem chasing the lines coming to and from it...

The vacuum ball resevoir is hard to find, it's buried in the area around the battery/washer fluid resevoir...you may have to move some stuff to access it. Once you find it though, you'll have no problem chasing the lines coming to and from it...

My dad hit a fox when driving my car and ripped up some plastic around the driverside front wheel well. He said that a black plastic ball fell off of it and he threw it away. Could that be why it is not working?

Yes, that missing vacuum tank (ball-shaped piece of plastic) is why your's wont switch, and it actually mounts under the battery tray. You access it from under the car though....you have to at least partially remove the left front wheel slash shield to get at it. And someone said earlier that the line is probably rotted on the first poster's car...dead on....look beside the battery...they always crack in that area.

By the way...this is my first post....My name is Bill....I am a G.M. and ASE certified professional automotive technician...I work for a Chevy,Buick dealer in central Ohio and I specialize in Electrical/Electronics,HVAC, and interior/exterior trim. I own a 1997 T-blazer 4-door 4X4, a 1987 Caprice Classic Landau Coupe (1 of only 3110 made) and my most recent purchase...a 1991 Lumina Euro 4-door! I am really liking the Lumina, I've always liked them and have been looking for a good buy on a first generation euro for a long time. Please welcome me?

Yes, that missing vacuum tank (ball-shaped piece of plastic) is why your's wont switch, and it actually mounts under the battery tray. You access it from under the car though....you have to at least partially remove the left front wheel slash shield to get at it. And someone said earlier that the line is probably rotted on the first poster's car...dead on....look beside the battery...they always crack in that area.

By the way...this is my first post....My name is Bill....I am a G.M. and ASE certified professional automotive technician...I work for a Chevy,Buick dealer in central Ohio and I specialize in Electrical/Electronics,HVAC, and interior/exterior trim. I own a 1997 T-blazer 4-door 4X4, a 1987 Caprice Classic Landau Coupe (1 of only 3110 made) and my most recent purchase...a 1991 Lumina Euro 4-door! I am really liking the Lumina, I've always liked them and have been looking for a good buy on a first generation euro for a long time. Please welcome me?

Welcome to AF Bill! Thanks for the quick reply. You seem to know what you're talking about when it comes to chevys. Great for a comunnity like this. As you said, the vacuum tank was "removed" from the bottom of the car along with the wheel slash sheild when the fox was hit. I guess i will just have to start looking at junk yards for a new vacuum tank.

Welcome to AF Bill. Any and all constructive posts are welcome, and it's obvious you know something about cars.

Thanks for reply and welcome to the forum.

We could use your help over here, lol.

Will take a look in next day or two and will let you know was I succesfull or not with it.

Welcome again, and give us a good advices.


Very sincerely,

Dino

Thanks for the warm welcome guys! Glad to be here.

Hey guys,

thanks for answers and infos.

Opened today the front left wheel, took it off and pull some plastic around wheel base off, so I found a broken thing which you refered like a plastic vacum tank.
I also opened and take off the guard thing from under the hood and took off the washer fluid tank and found right under where the broken peace of plastic is.

My next question is:

where to go to buy this plastic thing and what's to look for???
I think I can replace on my own, since I found it and now know how to get to it.
Just need to find the right part.


Thanks for you help guys again.


Very sincerely,

Dino

Either a junkyard or dealer as far as I know, but there may be some available in the aftermarket. It's called a vacuum resevior for the HVAC (heating ventilation and air conditioning). All it does is store vacuum, so you can use one from any car.....it is VERY common on many G.M. cars up till around 2000...now most of them are electrically controlled instead of vacuum...so there isn't a need for the resevior anymore.

The GM part# for the HVAC vacuum tank (that's GM's name for it) is 15973049, and it retails at the dealer for $27.23

Hey guys,

thanks for your help.

Did opened up and fixed it.
Didn't have to change this vacum tank, just a hose that was going to the tank.

Now the spouse is satisfied. Again.
LOL.

Thanks a bunch guys.

Very sincerely,


Dino

Would the HVAC problem also cause the rear defogger not to work?
Thanks

Welcome to AF!

It would not. Please start your own thread for help on that topic.