Is there another filter on an American Standard air handler

I change the return filter regularly.
I was in the attic this weekend and noticed for the first time the air handler itself has a slot marked filter.
No tech has ever mentioned a filter in the air handler.
I didn't open it (hard to get the cover off) but I will if somebody thinks there's really another filter in there. It's not exactly customer accessible.
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Ha, you better check.
We have a old house (around 105 now) and the central air was installed like yours, with the air handler in the attic. No one mentioned a filter in the unit either. The way they installed it for the returns was to use a pair of 20x20 frames in the hallway ceiling and flex all the way back to the unit. The attic isn't usable space, only access is with a ladder through a wood popup door in one of the closets. It's filthy up there.
The filters downstairs we changed more or less every 30 days and the system worked fine for the first 3 seasons.
In the next season we got one of those heat waves where it was in the 90's for several days in the row and the air just didn't seem to be coming close to keeping the place cool at all. Using a thermometer and sticking it across one of the vents, did show a low temp, maybe 52 degrees. The thing was, unless you wet the back of you hand and placed it next to the vent, you just didn't feel any cool air just standing a foot or so away.
I had a similar problem with a central air unit in a storefront I rented for a while as an office. The system was replaced once and they said there was a requirement to tap in an outdoor air source (never did find out if that was true) but they ran a small vent to the return side so some outside air would be drawn in.
The problem was, the way they attached that vent to return, it totally bypassed the air filter so after just a year or so, the A coil in the furnace was totally clogged.
Anyway I figured the house might have the same problem, maybe there was a leak in the return, sucking in the attic air with all the dust and dirt up there or something.
After inspecting the coil, which seemed fine, I noticed on the other end a tag saying something like "filter must be removed after installation".
So I took the cover off that side and after removing this 1" wide metal bar, there was a filter there. Not a regular paper/cardboard but made of plastic or nylon, both the frame and mesh. After I pulled it out, it was obvious this wasn't passing any air at all.
I was just going to toss it since the one sticker said to after installation but there was another tag on that metal bar (which holds the filter in place) saying to clean annually with water.
So I took it back downstairs, sprayed it clean with the garden hose and put it back. I figured it worked for 3 seasons and wasn't hampering things with it in place so it's now part of the yearly ritual of removing and cleaning before the season starts.
Here it is 13 or 14 years later and the system still runs top notch.
It saved my cookies, the reason it was clogged is eventually I did find a hole/tear in the flex return, that summer before locating the internal filter we had a raccoon roaming around and appears he started chewing on it. Was just in a spot that wasn't obvious.
-bruce snipped-for-privacy@ripco.com
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On Saturday, October 31, 2015 at 11:54:52 PM UTC-4, TimR wrote:

ible.
There should not be a filter in there but it wouldn't hurt to check. Some air handlers have a slot for a filter for situation like a closet installat ion. I found one in a unit once that must have been 10 years old and had b ecome so clogged the fan basically ripped it apart.
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