2008 Prius making loud noise-help

It is possible that the noise comes from the fans on the car radiator. When the coolant temperature is high and the radiator is clogged, they turn on more often. Have you checked the temperature when they turn on?

 

You should be able to know very quickly with your ears and your eyes if that noise is coming from that electric compressor with the orange cable going to it which you can put your hand on while it's running and nothing can hurt you there's no belt to rip your hand off or anything that's on the alternator a bit of ways from the air conditioning compressor you could unplug the fans for a second and see if the noise magically goes away the fan noise is going to sound like a lot of cards stuck in the spokes of bicycles usually the compressor noise if that's what it is is going to be a lot more whiny and squealy type of noise as there's nothing driving the compressor except an inverter inside of that big hunk of aluminum there's no belt there's nothing externally spinning usually these compressors don't make a lot of racket when they go out they just literally smoke and that's pretty much it they usually wind themselves out to death trying to spend or pump nothing. Sounds to me like something else maybe making the noise record a sound bite on YouTube and put it up wherever you post those kinds of things somebody will be able to tell you within seconds probably

 

If you spin the fans by hand (with the car off! and cooled down), do they make an unusual noise?

Has a prankster taped a playing card to them?

 

I guess the ace of spades.

 

If that's what it turns out to be, you'd better have an alibi.

 

The low line is the fat silver line That's supposed to be cold when the compressors running no matter what's happening inside the car if the air conditioning is on or the defroster is on or what have you that fat silver line that runs in between the engine and the transmission with the gray cap that says l on it I think that's your suction or low pressure side that's the side that gets cold the little skinny line way over there where the sight glass is that's the one that's bringing the heat out of the car that's going to be warm hot so if you're fat silver line is warm or body temperature or anything like that you're about 80° too hot so it sounds like your air conditioning compressor should not even be coming alive when you push the button with the yellow line above it you shouldn't even hear it spin up would seem to me and if it is I wouldn't run it like that because you're inverter is going to try and run into Oblivion 8,000 RPMs trying to pump nothing you don't want to be that guy you want to be pumping something gas refrigerant gas to be exact.

 

There's only a 1 in 52 chance that MAX2 would correctly guess which playing card if MAX2 wasn't the prankster who put it there.

 

Standing in front of the car the right side of the engine bay would be the driver side headlight the air conditioning compressor is over where the passenger side headlight is and way down at the bottom of the engine so that's at the opposite side of the car kind of doubting that noise is coming from your air conditioning that's low on Freon it shouldn't even be coming on the fans might come on but the compressor probably doesn't it's a safety feature.