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Used Cars for sale - Used Trucks for sale [3538857438] Buy Used Cars


- Chevrolet-Express Van

Forum Post
07/02/08 10:16


The fan switch works, you can hear air blowing but none comes out out of the fronts vents some thru the floor and some thru defrost.


Archived Replies

This post has a total of 37 replies. The most recent 25 are shown below, you can view the complete archive here: NO AIR FLOW FROM HEATING AND AIR THRU VENTS archive. Your feedback, comments, opinions and questions are welcome and encouraged.

This forum post has messages dated from 07/02/08 through 08/07/14, please be sure to read all the messages. If you feel it is old or outdated, please follow up with a question or comment and someone may be able to update it, or reply with newer information if you have it.

07/27/09 12:37

I have a 93 suburban with the same problem and need to know where the vacuum tubes that accuate the blower system are LOCATED in order to fix them. I have looked everwhere in the repair book and online.
08/04/09 07:19

my 1999 express had same problem. To fix mine I removed the engine cover and the vacuum line came across the top of the engine from the passenger side to the drivers side and connects to a fitting about mid engine just inboard of the valve cover. Right at the connection the hose was bad, cut off about an inch and now a/c is good as new.
08/19/09 02:16

Hey guys all these are wrong. Especially the one where the cold air blows through the defrost top and bottom. There is door that is electrically operated and the gears or motor goes out and wont let the cool air come out the vents. Just thought i would clear that up. I have the same problem and i am fixing it 2moro.
09/08/09 12:42

"Hey guys all these are wrong. Especially the one where the cold air blows through the defrost top and bottom. There is door that is electrically operated and the gears or motor goes out and wont let the cool air come out the vents. Just thought i would clear that up. I have the same problem and i am fixing it 2moro."

This is incorrect. The doors on the Chevrolet and most other vehicles are operated from the engine vacuum. If you don't have any air coming out of the dash vents, or it stops blowing from the dash vents when you are under acceleration, then you don't have enough vacuum coming from the engine to keep the doors in position.

When you lose engine vacuum, the door defaults to defrost.

There are no cables that operate this and it is not electronic.

The leak can be anywhere. It can be a dry-rotted or chafed line. You will just have to look for it... Listen for a hissing. Spray the lines with carb and choke cleaner... When the engine sound changes, you have found your leak.

Good luck.


10/19/09 19:38

Wow. I am getting this problem intermittently on our 1997 chev express with 5.7 liter V-8. Sometimes it works fine, then doors close up and no heat or ac come out. I bet it is a leaky vacuum line. It seems like something like vacuum is holding those flaps inside the duct system, then it lets go and wham heat only goes to windows. I'll check the vacuum lines and keep yahs posted! Winter coming on - gotta get this fixed.
10/22/09 14:46

Rear compartment only blows hi High. Low and Medium do not blow air using either switch (front control or 2nd seat control). Wondering where to look for defects. Wiring, Motor, Fuses...? And where are these? How to get access to them?
01/06/10 21:06

you guys are funny your telling him he is wrong when he is right i have seen all of this first hand in my own shop. ford typically vacuum chevrolet typically whats called a blend door actuator or even the dash switches sometimes fail kinda rare but happens the constant problem with the chev 96 or newer rigs is not going to be vacuum dont waste your time. atta boy clint you got it right on the money and tom your an idiot! especially for telling the guy that was right that he was wrong. i hope you read this some day.
03/21/10 18:06

I have a 1995 chevy g 20 van and I am having problums finding the blend door actuator..... Is it under the doghouse? I have had may people tell me different things and i need to get it fixed befor it gets to hot and my boys roast in the texas heat.

Thank you

06/01/10 20:33

Just had this same problem myself. I read all of the suggesdtions and went to investigate further. I found a two-sided vacuum hose disconnected on the passengers side under the dash. Someone had got there feet entangled under the dash. Blew air again after reconnecting it.
06/29/10 19:58

Jay, you nailed it. That "two-sided connector" sure looks like electrical wires to me, but whatever it is was disconnected under the passenger dash just like you said. Count my 2004 chevy express van fixed and blowing air out the front vents!
07/06/10 18:35

I have a 1996 Tahoe and was having the same problem and after reading the posts here I went and looked under the hood of my car and sure enough I was missing a vacuum hose from a connector next to the, as your facing the engine the left side of the carb there is a module comming out of the intake manifold. There were two hose connections one on top and one on the left side, both had a boots on them but the one facing back towards the cab looked like it was connected but on closer inspection there was no hose at all. You have to understand that air has never come out of the vents on my car the whole time I've owned it, so I know this did the trick. I felt behind the dryer on the fire wall and sure enough there were also two connections but only one had a hose on it, so I bought a three dollar hose from autozone and connected the two and low and behold we have air...

Hope this helps some of you.....


07/18/10 17:24

I have owned 10 97-2002 astro vans and this problem is always a bad vacuum hose that gos across the top of the engine. One crack and your srcrewed.

I guess I am the man!!!

08/02/10 11:40
Glenn Graham

I would agree with Jay. I have two company 04 and 05 express vans. When a passenger gets their feet up under the dash they disconect the vacuum line. I have the same symptoms with air blowing in the dash and it is easily fixed.
08/16/10 18:31

I was having the exact same problem with my A/C not blowing out of the vents, only the floor and the defrost. Anyway, I removed the engine cover and checked all the hoses , etc and they were in good shape. My problem was that I had installed a heavy duty battery and in doing so, I must have disconnected the "other" vacuum line that goes to the pressure storage ball or globe , under the battery. Hooked it back up and everything worked fine. Only took an hour to figure out that was the problem. I thought I heard a hissing, but couldn't tell for sure if it was air or a sound from the engine.

Good luck and start with the obvious/easy stuff first.

10/02/10 09:33
larry cechowski

1999 chevy express van fan only blows on high speed comes out of all vents but once in a while will not blow at all.
10/02/10 18:21
paul oldham

1995 chevy tahoe no defrost air.air works on other ducks
12/10/10 00:51

Yep, bingo! 2003 Express. Blower wouldn't turn off until unplugged nor switch distribution and blowing strength. Well, resistor swap for $30 solved the first problem, then scratched my head, google lead me here, checked under my passenger dash, and there it was, two rubber hoses withe plastic clip detached from another hose bundle. Click and boom, fixed! Thank you so much!

Tip: Don't run your blower on lowest, it wears the resistor faster.

01/13/11 22:25

Hey I have a 04 express van that the blower runs on high, but the air comes out like it is on low at any vent setting. I have good vacume and there is no line disconected. I have the front of the dash(air bag pulled) and the heater box cover off. I can see the door working with the motor on it. I can see three more doors working when I change vent setings and hot to cold. there are two vacume lins going up to the top of the heater box one is blk and one is pink, I can not get to were they go.Could this be my problum or it there somthing eles???? If it is those lins how do I get to them???? If any one could help me I sure would be thankfull.
03/22/11 02:33

I'm working on an 02 Chevy Express with the 6.5L diesel. It is giving me the same trouble as many of you have experienced. I have air flow through the defrost and floor vents, but nothing in the center of the dash. The blend door acuator is not to blame, nor is the air temperature actuator. I'm quite sure this is a vaccuum problem since the blend doors are vaccuum controlled, but have not been able to find a leak. The 2 way vaccuum connector checks out, as does the vaccuum pump. If the pump were at fault, the waste gate for the turbo would not work. I'm leaning toward a bad console, but i cannot hear or feel any leaks, and spraying ether accomplished nothing. This would be much easier with a gas engine, the diesel is so loud that it's near impossible to hear vaccuum leaks. It may also be the vaccuum door actuator, but i've removed it and it seems to work jsut fine. Anybody run into this issue?
04/15/11 20:47

i have a 97 chevy tahoe and when i turn the ac on low and medium air comes out, and when i turn it on hi the air dose not come comes out from the vents on the side pointing to the windows does any body know why?
09/23/11 20:45
Thank author of this post/comment"2004 Chevy Express Van heat and air only blow from defrost vent"

I have a 2004 V8 Chevy Express Van.

The fan, heat and AC only blew out the defrost vent as if the climate control switch had suddenly broken. Switching to blow from other vents had no effect. The problem was a disconnected pair of vacuum hoses.

There is a bundle of various colored small diameter vacuum hoses that runs up behind the heat duct work on the passenger side under the dash. There are several clear plastic connectors that join together and connect these hoses. The hose bundle fell down from under the dash where someone in the passenger side accidentally kicked and uncoupled a connector for a pair of hoses. I plugged the hose connectors together and the heat and AC immediately started blowing from the other vents. I strapped the hoses out of harms way using cable ties.

07/09/12 05:10
Marietta, GA driveway war!
Thank author of this post/comment"Battling in the DRIVEWAY again! 1997 chevy 3500 cargo van no air "

My 1997 3500 cargo van. So far this is what Ive done with my no air flow problem; inspected all the vacuum hoses I can get to. Checked the blend door actuator. traced the vacuum lines up to the back of the vent control, and all the places they connect under the passenger side dash. GOOD THERE.., The blower works and toggles from high to low properly. I noticed there might be a piece of duct missing under passenger side dash (air coming out of side from behind center of dash), also found two vac lines disconnected (brown and black together coming thru firewall to the main connection) One goes to a sensor or air switch under the hood. the other cant trace it but goes up into heater box. I re attached them in line with other brn, bk hoses form the vent control. What else can I check? Can I get air to blow without a working A/C? Thanks for reading, please help its hot when it rains!
08/13/12 02:48
New Hampshire
Thank author of this post/comment"That was easy1"

Whoever said to check by passengers foot area for hose disconnected was totally correct! Thank you so much!
01/20/14 01:01
Thank author of this post/comment"CHEV EXPRESS HVAC NO AIR"

1997 Chev Express Van - Just spent approx $450 and still have problem. Intermittently some door or doors closes in my HVAC and then even with fan on high tiny bit of air on any setting. Including defrosters - which can be a disaster! Does anyone know which door(s) this is and how to fix??? Blend door actuator?? Earlier Clint seem to have this nailed by did not get the detail and what to replace/fix. Thanks all!

BTW, swapped 4L80E trans in place of the weak 4L60E - no more waiting for the tran to blow :):):)

08/07/14 21:31
Thank author of this post/comment"it's the vacuum hoses"

Just read through this whole thing- I had the same problem, the air/ac was only blowing through the defrost and the floor.

I found a brown vacuum hose that actually looks like a thick brown wire under the passenger seat foot well. I was dubious that chevy would still be using vacuum actuation in a 2012 (chevy express 1500) , but sure enough, with a little digging, it had been kicked out of a connector where it was mated to another brown hose and a black one mated with a blank/plug.

re-connected them, started the engine ( to generate the vacuum) and the air vent control worked as it always did.

Thanks for the help folks!

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    Archived Replies

    This post has a total of 37 replies. The most recent 25 were shown above, you can view the complete archive here: NO AIR FLOW FROM HEATING AND AIR THRU VENTS archive. Your feedback, comments, opinions and questions are welcome and encouraged.

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