[Gordon Claunch]

I need some help , We just bought a new house, in the hallway where the Air conditioning return is located, you can look up and there is a red light on the drop down door.
I believe this is some sort of electronic filter system, it sounds like a damn bug zapper every now and then, I found very little on the web, but I did find mention of it.
I just want to make sure this is normal, have any of you ever seen something like this? It is different from anything I have ever had before.

Thanks,

Gordon