A/C question...

[Apathy25TX]

Hello All!

I'm just wondering if any of you have come across a hissing sound coming out of your LS Dash? I'm pretty sure I don't have a snake or a mad possum inside my dash so i'm thinking it's got to be related to the A/C. It sounds like something is pressurizing. I have also noted that my A/C doesn't blow cold air on a very hot day when before it used to have no prob. I'm thinking a simple recharge, but what would explain the hissing sound?

Thanks in advance!

 

[NYC LS8]

Hissing sound would be some sort of vacuum leak I would think.

 

[joegr]

That would be the normal thought, but unlike many cars, the LS doesn't use any vacuum servos in the climate control. I can't think of anything under the dash that uses vacuum. The brake booster is the only thing. A leak there would be very bad. After you turn the engine off, do you still have one good (easy) press of the brake pedal left?

 

[pektel]

I hear the hissing sound too, but it's just the climate control opening/closing.

 

[nightriddah]

Hello All!

I'm just wondering if any of you have come across a hissing sound coming out of your LS Dash? I'm pretty sure I don't have a snake or a mad possum inside my dash so i'm thinking it's got to be related to the A/C. It sounds like something is pressurizing. I have also noted that my A/C doesn't blow cold air on a very hot day when before it used to have no prob. I'm thinking a simple recharge, but what would explain the hissing sound?

Thanks in advance!

It is very possible it could be A. your compressor or B. your evaporator.
Not positive. Either way, hope it's neither!

 

[Apathy25TX]

That would be the normal thought, but unlike many cars, the LS doesn't use any vacuum servos in the climate control. I can't think of anything under the dash that uses vacuum. The brake booster is the only thing. A leak there would be very bad. After you turn the engine off, do you still have one good (easy) press of the brake pedal left?

My brakes seem to be fine, but i'll double check the next time to turn off my vehicle. The hissing usually comes out when i turn my car on. It'll hiss that one time and then everything will be good. I'll turn off my a/c and turn the car on for a day or so to see if it's a/c related. As for the a/c valves, those sound like a creeking door closing.

 

[pektel]

yeah, you're right. It does sound more like a creaking door. But that creak sound - at least in my car - is accompanied by a hissing noise. We must be talking about 2 different things.

 

[Garbone]

The owners manual says there will be sounds from the dash, arfer the key is removed. My 04 has a sound that lasts for a few seconds, that sounds like a hiss. I believe it is simply closing a door, after everything is done.
If the hiss is constant, with air moving, maybe something is lodged in there, causing the noise, when air is moving??? A partially open, or closed door could cause an air noise.
I also found a duct that was broken, and had fallen off the next piece, above the passenger side foot well. I fixed that, and it quieted some.
I work with air movement in my job, quite frequently, and even a pc of tape can make a loud air movement sound...hissing is a good description.