HVAC question Re: air filter

Bubble gum will fix it

Replace your filter, heathen.

Is it more of a thud or a ding?

Like the other poster said if it's a thud sound it is likely the filter frame slamming into the return frame.

Git yerself some of that foam tape and stick it along the edge of the register where the filter sits. It'll create a good seal and eliminate the thump.

quote:

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When the AC shuts off the filter likely is settling into the return grill. So when it clicks on the vacuum is sucking the filter back into the collar of the grill. Or it could be just the filter flexing depending on the material.

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Very likely this as my HVAC return filter grill did the same, even with a low fiber spun MERV 4 filter.

My cure was to place 2, MERV 4 filters on top of each other, inside the grill as there was sufficient space to place 2, 1-Inch filters on top of each other inside the collar and still close the return grill. About a year ago I started purchasing 2 inch thick pleated MERV 8 filters. There is no space for the filter to move up and down.

That may or may not be a simple solution for the OP depending on the space within the collar.

Also it might be only an issue for the OP if using a high MERV pleated 1 inch filter. If so try a single 1 inch MERV 4 fiber spun filter and see if continues.

My return is in the ceiling and it's quite aggravating. I duct tape the filter to the return duct collar and that stops it from happening with mine. creates a better seal too.

If filter moving, when the unit kicks on, use blue painter tape. Tape the filter to the frame track.