How to keep mice and rats out of your outside AC unit

What the numbers show

Counted from the threads quoted below. How we count

• This comes up 27.1× more often in r/HomeImprovement than across the site as a whole.

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

1. 1
   Checking inside the unit weekly through the top fan grille
2. 2
   Peeking in and vacuuming out leaves and pine needles
3. 3
   Sealing entry points with hardware cloth or steel wool
4. 4
   Using cat hair or cat waste around the perimeter as a scent deterrent
5. 5
   Using expanding spray foam with cardboard or drywall saws
6. 6
   Using rust-resistant copper mesh combined with windows and doors spray foam
7. 7
   Using duct seal putty where the lines enter the home

In their words

Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.