patsfan

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

CHUXDRM

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.

patsfan

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.

patsfan

Ttt

BitViper

Ahhhhh snakes on a plane!...

Get thes MF'ing snakes offa my plane!

Sorry..

Venomous

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.

Evil-Twin

The OP said all of his vacuum control doors are working... the hissing is a give away of a vacuum leak but its not the control door line. atleast according to the OP.

Venomous

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.

CHUXDRM

As I said in my first post, it sounded like vacuum leak to me, but not knowing where it might be comeing from, or how hard to get to. I asked a dealer about it, he said we could run up quite a labor charge just tearing into dash to investigate, so we let it go.

Your info about the hose connections on the back of the head unit sounds like a possibility. I may do some digging myself.

Thanks.

patsfan

I actually installed a new radio in this car shortly after buying it so this could be a possibility . 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 ?

patsfan

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.

lucky131969

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.

patsfan

Damn I was hoping it was what Venomous posted . Thanks for the tip Venomous.

Any other idea's guys ??

Venomous

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.

patsfan

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

lucky131969

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?

patsfan

Unfortunatly I don't , wish I did though. I'll get one eventually.

Venomous

I know you have to remove the center console, knee bolster under steering wheel, and the trim panel. Once behind the trim panel, on both sides of the steering wheel area there is a bolt 7-8mm that connects the IPC to the dash, that have to be removed prior to pulling on the IPC itself. After you remove those 2 you should be able to pull gently on the IPC to remove. Just pulled mine a few weeks ago to fix an intermittent tach signal. I do not have HUD though so take care to see what that entails. If you need to pull the IPC out further you will prolly need to lower the steering column as I could only get it out about halfway.

patsfan

Thanks for the info guy's!!!! I'll be playing with it tonight and this weekend.

dmarkshark

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.