This noise just started yesterday on our 2007 Prius. Seems to be coming from dash area and not the engine, but I could be mistaken. It sounds electronic in nature, like a pump or something being clicked on (but I'm clueless). Here's a video of the sound, you'll hear it most clearly from :9 to :16 seconds and may need to crank your volume some:
I talked about this before in another forum. I got the a/c replaced in my car and they took out the dashboard. I haven't heard it since. They must have adjusted something.
I don't know what it is but I hear it too in my car. It's not the vent door it's not the brake actuator it's not the chrs pump it's something in the dash though behind the mfd and it makes the sound with the ac both on or off. It's not real serous as it has not thrown a dtc so have not worried about it to much.
When I had the problem, I thought a rat or something was moving around in the steering column. I wasn't moving, the it knocked and rattled.
Who's prodigyplace? Mine hasn't made the noise in a while. It comes and goes. Its not in the engine compartment its in the dash more on the passenger side. Does it will ac on or off. Does it with blower motor off. Vent door in any direction.
That's your air mix damper control servo motor that's making that noise if it rattles back and forth like that. Mine does that too. It was doing it a lot last summer but hasn't done it anymore. Posted via the PriusChat mobile app.
@Prodigyplace is a member that seems to know a lot about the technical parts of the Prius. My noise was on the driver's side very close to the steering column.
Sorry I did not answer earlier but I forgot and was outside working on this beautiful day. I am flattered, but I am a Prius newbie. I have only had mine since October. My son, though had a Gen 2 Prius and now has a Prius v. so I am not a complete newbie. I search online in the owners manuals and, when age permits. I remember other PriusChat threads. This hearing aid wearer is definitely not a sound expert. Sorry, I cannot identify the sound. On my Trim Two te noise would likely be drowned out by tire noise.