That whistling sound

When I first moved into the beach house I renting right now, there was this irritating whistle genre sound coming out of the air vents every single time the central heating plus air conditioner idea device would kick on.

For the first week I put up with it thinking this may be normal plus will work itself out.

Well, that did not happen. So, looking into this further I found that the solution was simple. And I was cheerful I did not waste money on having to call a heating plus air conditioner supplier. Because it turned out that the air vents were not fully opened! And in turn, the air flow would be blocking everytime the central heating plus air conditioner idea device came on. So I got up on a ladder, went around the house plus opened up every single air vent 1 by 1 to the fullest. Then after this, when the central heating plus air conditioner idea would come on it no longer made the whistle noise that had been going on since the day i moved in. Had I called the local heating plus air conditioner supplier, this would have cost a few hundred dollars just to go around the house to open up a few lousy air vents. I think you are thinking shouldn’t the landlord or management pay for heat plus a/c service? Ordinarily yeah, but I have a special low rental rate with the clause that I take care of any issues that may arise around the house. So that is what I am doing now.
HVAC worker