I'm not familiar with your unit, but the A/C filters for our Pinnacle are in the return air vents, (they look like residential vents). Ours are located in the living room area in the ceiling, one on each side of the coach. There is not a filter for the furnace, it is vented from the outside at the furnace.
Hope this helps.
2015 Pinnacle 36FBTS
2015 F250 SD Platinum 4x4 - 6.7L PSD :
Titan 50 Gal. Fuel Tank
Slotted and Dimpled Brake Rotors
Air Lift LoadLifter 5000 Ultimate Airbags with WirelessAIR Controller