Whistling or thud noise after putting in a new air filter
Installing a new air filter can be too restrictive, causing a horrible whistling sound or a loud thud from the HVAC unit as soon as the filter is put in or a cooling cycle ends. These disruptive noises happen exclusively when the filter is active and stop entirely when reverting to a less restrictive filter.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Reverting to the original, less restrictive air filter
- 2Using a standalone air purifier for allergens instead of upgrading HVAC filtration
- 3running the system without a filter
- 4switching to lower-rated fiberglass filters
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“Now, however, when the AC completes a cooling cycle, we here this "thud" noise coming from the ceiling where the HVAC is.”source ↗
“I put the MERV 1 back in and no thud. I's guessing the 1 inch thickness was too restrictive?”source ↗
Where this came up
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