I am trying to understand exactly what makes a filter switch work guys. This is a Honeywell AP4576-2255. This is in a big air handler that is only 9 months old. I was told today to reset the filter switch by covering up the filters 75% and then setting the switch. The switch is normally open, and when I suck on it it closes. Now, due to the way that this Trane Airhandler has been set, I cannot access it like I should be able to, so I have to remove the filters to get into it. Therefore, I had to block the coil off 75% with plastic. Now, to me, this seems like it would pull more on the filter switch which would cause it to close instead of open.

Of course I did the natural thing and jumped out the switch and it still alarmed, which again makes me wonder if it is supposed to be normally open until the fan pulls hard enough on it (due to not being able to get air through the filters) that it closes the switch. Please help me figure this simple thing out if you have set one up before. I know it is easier than I am making it, I just don't really have much info on this switch because it was supposed to be a JCI switch anyway. Thanks