I have recently noticed that there is a loud, high-pitched whistling sound coming from under my hood that has progressively gotten worse over the weeks. At first, it would only occur when I had my AC or heat on and would stop immediately once i turned the AC/heat off, and will also happen from time to time when I accelerate. Now, this noise is happening right when I start my car and takes a few seconds to stop.
My prime suspect would be a disconnected or cracked vacuum hose.
Are there any other symptoms, such as an engine that is idling rougher than it used to, and/or a lit-up Check Engine Light?
Incidentally, revealing the make, model, model year, and odometer mileage of your vehicle is a good idea if you are looking for really specific responses.
Sounds like a slipping belt to me.
^
Yes, if the noise could be described as a shrieking sound, then I agree that it would likely be a slipping belt.
I was assuming that the noise really is a whistling sound, but I suppose that one man’s whistle could be another man’s shriek.