gas furnace running without air filter?

[flitz]

Please advise me on the best air filtering strategy for the following setup in my new home:

I have a Carrier Crusader furnace (model 58SSC090-GC, series 110) sitting on top of a Carrier Electronic Air Cleaner (model 31KAX016100). The incoming air seems to come from the back of the air cleaner unit where I think is an opening towards the top, but because of the low accessibility of the area (only from the front) I cannot trace the duct work. Is this were the air is supposed to come from for this unit? The electronic air cleaner looks very clean inside. I contrast, the furnace looks very dirty as far as I can tell given the limited view. Now the issue: the power control light of the air cleaner stays off even when air cleaner switch is at "on". How can I find out it's actually running? Next to where the front panel is plugged into the power outlet of the air cleaner main part, there is an empty hole in the air cleaner. Is this maybe where the electric wiring is supposed to go? If not, where does this unit get the power from? Does it get power from the furnace above? With the panel removed from the air cleaner there is no voltage in the outlet of the cleaner main part while the furnice is on but not active. Is this normal? Let's assume the electronic air filter is either not working or I just keap it switched off, could I just add a disposable air filter down there?

Please help. If pictures would help let me know.

[furd]

Yes, pictures would really help. Be sure to have both close up and pictures from a far enough distance that we can see all parts as they fit together.

Electronic filters will trap the smallest of particles but the more they trap the less effective they become. As a result they really need to be washed about every two weeks. Since few people are up to the task often the electronic air filter is only slightly better than useless. Fortunately, it is usually pretty easy to remove the "cells" in the case and substitute a "box" filter. The box filter is like any other media filter in that as it becomes dirtier the more dirt it traps although it also becomes more resistant to air flow.

One thing, if the indicator lamp on the electronic filter isn't lit the filter is doing nothing.

[flitz]

Furd, thanks a lot for your advise. Just in case others encounter a similar situation, here what I found out and did:

Yes, the air filter takes in the air from the back. Here the online manual: http://www.docs.hvacpartners.com/idc.../31kax-8si.pdf

Yes, the power light only goes on if the air cleaner is operiation, which starts about 5-10 seconds after a heating cycle. So the furnace controls and powers the air filter. I still don't know what the hole on the filter's side would be good for.

I have been running the air cleaner for 2 month now without cleaning, I think I should do that soon. I it's very dirty, I might replace it with the recommended box filter.