Whistling noise from engine compartment... what can it be? On 03 AWD Vibe

[jasonisnuts]

I have a 2003 AWD Vibe with 180,000 miles on it, in Minnesota. It actually runs suprisingly well, except for when it gets above about 80 degrees outside. Once it gets past 80, whether I run the AC or not after a certain period of time (it can be long or short, there's no pattern to it) there will be a whistling noise coming from the engine compartment. Typically I will be driving, then come to a stop, and it's at the stop I can hear it. Sometimes revving at a dead stop will make it go away for a second, but as soon as it idles it comes back. When I continue driving it goes away, except for when I am not actively on the accelerator, so like when I am idling down to a stop or at a stop. The last time it happened I popped the hood and listened from every angle I could to try and figure out where it is coming from. I think it may be coming from the cruise control.... here's a pic of where I think it is coming from, the cruise is in the center. (Yes I need to add break fluid and even when full the car has made that noise, so I don't think it's the break fluid pump...)

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[BlueCrush]

Mine is more of a tone that rises in pitch as I am at a stop light. Always had it since day one. My guess is something to do with the vacuum lines. It never affected anything on my AWD Vibe.

[prathman]

There are a number of vacuum lines in that area. I'd try moving them around a little one at a time while it's making the noise and see if there's any change in the pitch and/or volume.

[Whelan]

I get the picth like BC. I put it off as vacuum lines cause it does nothing, just whistles at you a bit.

[dianebrat]

thank the heavens... i am *not* crazy...(ok, maybe I am, but not in this instance)I've had the same weird experience since spring, a strange almost melodic, almost, whistle, but much lower tone, it could almost be brakes that are scrunching, but they're held down tight.you guys are the best, you have me thinking this "whatever" is what I'm hearing.

[RePo]

I've always used a can of either (starting fluid). Spray it around the vacuum lines. It will evaporate quickly, and if you find a vacuum leak the engine will respond by reving slightly when the leak takes in some starting fluid.