For the last 7 years or so, we are infiltrated with black fungus gnats (identified by exterminator) on the first floor of my house. I have 2 a/c units on the first floor. I put 3 flat-style window fly paper on the window above the a/c unit and they are completely covered with the gnats. These gnats will absolutely drive you crazy because they try to get into your nose & mouth (I'm assuming to breed). I'm on a lot of Zoom calls and I look like a lunatic anytime I talk because when I open my mouth, they start to come at me.

I've had window air conditioners on the first floor for probably 20 years and didn't have the gnats until 7 years ago. I got 2 new LG (LW1216ER) air conditioners last year thinking it was the air conditioners I had. This didn't help. If anything, it is worse. I am in the process of making sure that the windows are air tight but I did this last year and we still had the problem.

The exterminator said that it's because the air conditioners aren't tilted enough so I took one out to tilt it more. They have 2 u-shaped brackets at the bottom of each a/c unit on either side. Each has has a screw going through the bottom of the "u" which can be used to adjust the height. We aren't using the screw because the bracket was already sitting on the sill. Yesterday, I took the a/c units out to move the 2 brackets back on the a/c to try to tilt it more but now they aren't even touching the sill. The a/c cannot tilt back any farther because the lip that sits in front of the window where it closes on the a/c will not allow the a/c to tilt any further.

When I took the A/C out yesterday, there was a lot of standing water which I cleaned up. I saw no evidence of insect activity in the water or pan, but I don't know if I would see larvae since the gnats are so small. While I was cleaning the pan out, I realized there was no drain hole. In reading the LG instruction manual, it says "Do not drill a hole in the bottom pan. The product is designed to operate with approximately 1/2" of water in the bottom pan. There is no need to add water if the pan is dry." So these units are installed as they should be.

The a/c units upstairs do not have this problem. Also, my mother's room, also on the first floor but in the back, has no A/C. When I open the window she gets the gnats coming in (no screen in the window right now). She isn't anywhere near the front a/c units. Also, I have no house plants.

So, the question is, are they breeding in the a/c units or are they breeding outside and just getting in through openings around the a/c unit?