Hissing sound inside dash
Thread Starter
Drifting
Joined: Jun 2005
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From: Swanton VT 2000 Navy Blue Mettalic M6 / 1991 Auto - Steel Blue 68,500 R.I.P
Hissing sound inside dash
OK guys i have a hissing sound that you don't really hear until the cars been running for 20-30 minutes ( it happens if its just in neutral or while driving). When I turn on/off the heater controls the hissing sound will come and go. Some times when I turn the heat controls on its hissing other times its not. Its like there's no rhyme or reason but it does hiss more often then not. I've taken out the radio and it sounds like its coming from behind where the tach is but is truly hard to pin point. I have checked for codes and it doesn't have any. The heater seems to be working fine and airflow comes out of all the proper places when I hit the mode button ( floor, panel, defrost and so on).
Any help on this would be great appreciated
PatsFan
Any help on this would be great appreciated
PatsFan
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Joined: Sep 2006
Posts: 545
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From: Carlisle, Iowa
Very good question. . . I have the same issue. It seems to have something to do with the "heat" mode rather than A/C mode, because that's when it seems to happen. But it will hiss for a few minutes, then seem to stop.
I wonder if it's a vacuum hose leak when it's trying to close or open an air door, or when changing modes. But I don't know how all that works in there. Air and heat all seem to be working okay.
I'll be interested in any further responses.
I wonder if it's a vacuum hose leak when it's trying to close or open an air door, or when changing modes. But I don't know how all that works in there. Air and heat all seem to be working okay.
I'll be interested in any further responses.
Thread Starter
Drifting
Joined: Jun 2005
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From: Swanton VT 2000 Navy Blue Mettalic M6 / 1991 Auto - Steel Blue 68,500 R.I.P
Very good question. . . I have the same issue. It seems to have something to do with the "heat" mode rather than A/C mode, because that's when it seems to happen. But it will hiss for a few minutes, then seem to stop.
I wonder if it's a vacuum hose leak when it's trying to close or open an air door, or when changing modes. But I don't know how all that works in there. Air and heat all seem to be working okay.
I'll be interested in any further responses.
I wonder if it's a vacuum hose leak when it's trying to close or open an air door, or when changing modes. But I don't know how all that works in there. Air and heat all seem to be working okay.
I'll be interested in any further responses.
My doesn't stop after a few minutes, it will go on for hours unless I start hitting on/off button on the climant control. Then most times that still wont get it to stop. I'll have to look closer but I'm almost possitive that my does it either on heat or A/c function.
Pro
Joined: Dec 2009
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From: Waco Texas
OK, I did have this problem and whether or not it is the same I am not sure but I will tell you my fix. AS someone above posted I removed the center console and the radio to see behind there. Everything looked OK. Well, I removed the climate control head unit and low and behold I found the hose that had come undone from the control unit and was leaking vacuum. Plugged it back up and I was good to go and have been for about 3 months now. I assumed that when someone put the radio in, they accidentally unplugged this hose and never knew about it. I think the same install unplugged my FUEL DOOR release button control when removing the center console. Good luck and hope this helps.
Team Owner
Joined: Mar 2001
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From: small town in S.E Pa. PA
St. Jude Donor '03-'04
OK, I did have this problem and whether or not it is the same I am not sure but I will tell you my fix. AS someone above posted I removed the center console and the radio to see behind there. Everything looked OK. Well, I removed the climate control head unit and low and behold I found the hose that had come undone from the control unit and was leaking vacuum. Plugged it back up and I was good to go and have been for about 3 months now. I assumed that when someone put the radio in, they accidentally unplugged this hose and never knew about it. I think the same install unplugged my FUEL DOOR release button control when removing the center console. Good luck and hope this helps.
Pro
Joined: Dec 2009
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From: Waco Texas
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Pro
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From: Carlisle, Iowa
His doors may be working as far as switching from Defrost to vents to floor, but may not be actuating the damper door for the temperature separating chambers from A/C coil to heater coil. That is what I was kinda getting at. There are multiple hose packs on back of the head unit and mine isn't even the electronic version.
Your info about the hose connections on the back of the head unit sounds like a possibility. I may do some digging myself.
Thanks.
Thread Starter
Drifting
Joined: Jun 2005
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From: Swanton VT 2000 Navy Blue Mettalic M6 / 1991 Auto - Steel Blue 68,500 R.I.P
OK, I did have this problem and whether or not it is the same I am not sure but I will tell you my fix. AS someone above posted I removed the center console and the radio to see behind there. Everything looked OK. Well, I removed the climate control head unit and low and behold I found the hose that had come undone from the control unit and was leaking vacuum. Plugged it back up and I was good to go and have been for about 3 months now. I assumed that when someone put the radio in, they accidentally unplugged this hose and never knew about it. I think the same install unplugged my FUEL DOOR release button control when removing the center console. Good luck and hope this helps.
. I'm confused to where this hose is though. I never remember seeing a vacuum hose on the back of my "climate control head unit" where abouts does this hose go on ?
Thread Starter
Drifting
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From: Swanton VT 2000 Navy Blue Mettalic M6 / 1991 Auto - Steel Blue 68,500 R.I.P
Is this the head unit your talking about ? If so i can't see a loose hose or where a hose would go.
* excuse the poor photo's, Iphone is only camera I have at the moment.
* excuse the poor photo's, Iphone is only camera I have at the moment.
Tech Contributor
Joined: Jan 2007
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From: Dyer, IN
There are none on the auto climate control. Obviously Venomous missed your first post about pushing the "mode" button. He was referring to the manual control panel.
Thread Starter
Drifting
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From: Swanton VT 2000 Navy Blue Mettalic M6 / 1991 Auto - Steel Blue 68,500 R.I.P
Pro
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From: Waco Texas
Thread Starter
Drifting
Joined: Jun 2005
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From: Swanton VT 2000 Navy Blue Mettalic M6 / 1991 Auto - Steel Blue 68,500 R.I.P
Sorry bout the info regarding a non electric control head, skimmed past that part. I would believe ( not sure) that there still is some kind of vacuum head somewhere to move doors and vent selection? I'd think the climate control head unit jsut send a signal to another box that controls the dampers. If need be the IPC (instrument panel cluster) can be removed with a couple screws and removing the center console and knee bolster if the hissing sounds to be coming from behind there.
Dont be sorry I appreciate anything info I can get. I didn't know it was so easy to remove the speedometer ( IPC) , I already have the bezel out and the trim peice below the steering whell. If I'm able to remove the speedometer it will be easy ( I think lol) to locate where the hiss is coming from. Does any-one have a link to directions to get the speedomiter out?
Thanks
, PatsFan
Tech Contributor
Joined: Jan 2007
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From: Dyer, IN
Dont be sorry I appreciate anything info I can get. I didn't know it was so easy to remove the speedometer ( IPC) , I already have the bezel out and the trim peice below the steering whell. If I'm able to remove the speedometer it will be easy ( I think lol) to locate where the hiss is coming from. Does any-one have a link to directions to get the speedomiter out?
Thanks,
PatsFan
Thanks
, PatsFan
Thread Starter
Drifting
Joined: Jun 2005
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From: Swanton VT 2000 Navy Blue Mettalic M6 / 1991 Auto - Steel Blue 68,500 R.I.P
Why not isolate, instead of taking the dash aprt randomly? You can plug the vacuum line before, or after it comes into the cabin, and see if the noise goes away. That way, you'll know it's vacuum related for sure. Do you have a service manual to help you locate the components?
Unfortunatly I don't , wish I did though. I'll get one eventually.
Pro
Joined: Dec 2009
Posts: 606
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From: Waco Texas
Dont be sorry I appreciate anything info I can get. I didn't know it was so easy to remove the speedometer ( IPC) , I already have the bezel out and the trim peice below the steering whell. If I'm able to remove the speedometer it will be easy ( I think lol) to locate where the hiss is coming from. Does any-one have a link to directions to get the speedomiter out?
Thanks,
PatsFan
Thanks
, PatsFan
Last edited by Venomous; Apr 22, 2010 at 12:20 PM.
Burning Brakes
Joined: Jun 2010
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From: Rockwall TX
Just an idea, but why not start with the electronic vacuum selinoid under the passanger side and work with each line to see if you can isolate it, as mentioned above. I can get you the infor on the colored lines so you can see what each goes to, but not until later tonight if you need that infor.