Furnace Filters

[Marks mobile suite]

Have an 05 MS RE3 and had to turn on the furnace for the first time this season. Other than the bitch of a filter to get to above the Refrig. and on the back of the shower wall, is there another one to find and clean??

Anything I need to do maintenance wise on the furnace??. I assume the alarms would have gone on if it was not venting correctly or something. Kind of funky smell when on.

Thanks Mark :?: :?: