My window AC is rattling the whole window!

Last updated on March 10th, 2024 at 02:59 pm

Hi, I have a Frigidaire 7000 btu AC unit that rattles the whole window. I know the windows are old and I need new ones, how can i prevent the rattling without replacing the windows?


Hello Frank,

Rattling can be caused by two things: the vibration of the mechanical parts inside the unit which causes the frame to move, or the parts themselves becoming loose and moving around within the unit. The second one isn’t as common as the first one, but fortunately there are some things you can do.

  • Augment the padding on the bottom of the unit, where it sits on the sill. A lot of vibration comes from here, as this is where the “dead weight” of the unit is. Most have foam, if it is worn, place heavier foam in its place.
  • Place or replace foam or thin insulation at the top of the unit, where the window glass actually meets the unit. Make sure the screw is tight and the insulation is snug. If not, this rattles the glass somewhat violently.
  • Make sure the window is “locked” down onto the unit. This is done with an L bracket and prevents slippage.
  • Reinforce the pane, especially if it is breaking apart or splitting. Old wooden window frames that come in pieces often fall apart in pieces. When the wood starts splitting because of water damage, age, or both, the wood rattles. It will be near impossible to put the wood back together, so either fill it with sturdy wood putty or use something else to fill the gaps. Believe it or not, pennies often work great.

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