I finally got fed up with the repeated malodor, and as the service department at the dealership I'd purchased the vehicle from had serviced the system three times and the problem persists. I first called American Honda to open a case with them to resolve it. So far, the case manager still hasn't called me back after our initial discussion, after which he said he'd talk with the service manager and get back to me.

Tonight I pulled out the cabin air filter (same one reported at 9,589 miles) and noted it still looks dirtier on the outgoing side than on the incoming side, counter to every other filter I've replaced in cars or home. I also removed the blower assembly and the front passenger foot well outlet. I sniffed the cabin air filter, cabin air filter holder and blower assembly to see if the smell was coming from there. None seemed to be the source.

I got my nose as close as I could to the evaporator box and noted a slight moldy/mildewy smell. I tried getting my portable flexible bore scope through the front passenger floor vent outlet to see if I could get a look at the outgoing side of the evaporator and also at the heater core but I couldn't feed it into the chamber. It couldn't get a good look at the incoming side either as its built-in lights are too weak to light it up.

I was able to get some OK shots with my iPhone (attached). There seems to be a discolored region towards the middle and bottom of the evaporator, which may be residue from the cleanser the dealership used on 10/31/2014 at 5,254 miles. The technician had said a lot of junk got washed out, though of course, this wasn't noted on the service receipt. It could also be residue from what originally was the source of the rotting meat smell. I suspect what could be in the box is on the outlet side of the evaporator.

I also noted they didn't replace one of the nut/washer fasteners that holds the blower assembly in place (the top-right one when looking through the glove box hole.

Anyway, I ordered a new cabin air filter from a Honda dealership who sells parts on-line for a discount. It costs about $22 versus $34 that the parts departments at the local Honda dealerships would sell it for.

Yesterday the moldy smell started returning. On my commute into work, I suddenly got an intense sharp stabbing pain in the sinus above my left eye after I started running the HVAC fan with the windows closed. The pain was strong enough to make my left eye tear. The pain would not go away until I opened all the car windows with the car moving so the cabin air was refreshed via the open windows. After I'd cleared the air, the pain went away quickly. I figured it was likely something coming out of the HVAC system, so I put the fan on its highest speed while the windows were open.