Q: My 2016 Toyota Camry had a stagnant water smell coming through the air vents. I asked the service center Not to use any fragrances

This is something I always do in place of perfumed disinfectants. My other half is also sensitive to perfumed sprays. I use a name brand household spray disinfectant. They are available in different scents that you may be less sensitive to. I repeat this process a couple of times per year, or whenever it starts becoming a problem. First, turn the a/c on Recirc with the fan on medium to high speed. Spray the disinfectant down near the floor under the dash on the passenger side. When you set the system into Recirc, the air is drawn in from the heater ducts. Spraying down under the dash gets it pulled up into the a/c evaporator. I do that a few times. Then move the temperature selector to Hot and repeat. Once you’ve done that, switch off the Recirc feature and open the hood. Fresh air for the heat and a/c system is generally drawn in near the passenger side at the base of the windshield. You may even see some sort of grille in that area. With the fan still set on High, spray some more disinfectant in that area so it gets drawn in with the fresh air. Do that a few times then switch the temperature selector back to cold air and a/c on and spray some more. Once you’re done, allow the car to run with the a/c on, the fan on high speed, and the windows open for 5-10 minutes.