I had the same "smell",, bought new 2009 Bighorn 3410re and had the dealer install the front A/C, after using it for awhile and not being able to find the source of the odor, I took the A/C inside the bedroom cover off and discovered that the unit was drawing air from the attic, it was not sealed correctly, after sealing the inside I climbed onto the roof and discovered that the vent pipes were not high enough and were not caulked either, allowing the bedroom A/C to draw vent odor into the attic and then through the A/C into the bedroom, after these two fixes no more odor,
Mark