My air vents in my kitchen have been recently making a squeaking sound when the heating and air conditioner plan turns on, then it has been driving myself and others up a wall to be honest! I honestly could not figure out where it was all coming from, then every time the heating and air conditioner plan would turn on, the air vents went squeak! At first I was thinking there may be a mouse in there or something enjoy that… But, I just had my heating and air conditioner ductworks evaluated plus cleaned. I get my ductwork cleaned out every 3 months, and that 3 month time period had just happened. I honestly did not guess what was going on! I went and evaluated the air vents in some other rooms, and none of those were making that high pitched squeaking noise… The more I looked around, I finally figured it out! It happens to be that I had the air vent closed off! There was this little switch sort of thing, then all I had to do was pull it, and the air vent would open and close! I stood up on a chair and pulled the switch. Then, there was no more squeaking! The air from from heating and cooling plan was trying to blow out a half closed air vent. This was making the noise! I was so happy I figured it out and fixed the problem. I was pretty close to calling a certified heating and air conditioner specialist to come have a look. I am so happy I did not do that!