air cond needs to be turn on at least once a week, just to lubricant & maintain the system.
The simplest thing to do to get rid of the odor is to go to your local autoshop and ask for a air vent spray (about $20). then just follow the instruction (spray them into the vents, inside & outside the car).
Also there's another trick, everytime after using the Air Cond, I turn off the A/C, keep the fan running for a minute, switch the air circulation from Inside to Outside. Turn off the fan and Done.
My camry had this problem couple of years ago, but now it is superb & back to new smell
