B0sko

I was on my way home, and just before entering the last roundabout, I heard a loud scraping noise (not metallic, more like a 'plastic scraping' sound) and felt some vibrations in the car. I pulled over, turned off the engine, and started it again. The loud 'plastic noise' was gone, but I noticed that the fan wasn't blowing through the vents—there was neither cold nor hot air coming out. I immediately thought the cabin blower fan was broken. However, I turned the engine off and on once more, and then everything went back to normal—meaning no plastic noise, and cold air was blowing through the vents again. But I opened the hood and noticed a sound I didn't recognize: https://www.youtube.com/shorts/HpBd58aZ32c It's hard to describe, but it reminds me of the sound of a VW Beetle accelerating, or some sort of relay/electrical buzzing. And I'm pretty sure that the sound comes from breake-fluid refilcap area. Where is this sound coming from, and could it be connected to the fan suddenly stopping?