Consumer Reports highlights that moisture entering the vehicle's evaporator coil is often a primary culprit. This component of the heating and cooling system is designed to drain water away from the car, but if water becomes trapped, it can lead to mold growth and bacteria accumulation, which causes that musty odor.
To address this issue, start by setting the fan to a low speed and opening the windows for ventilation. Spray disinfectant into the air intake of the air conditioning system, located at the base of the windshield near the wipers.
With the fan running, apply the disinfectant to both sides of the air intake, allowing the system to draw it in to kill bacteria and neutralize the odor.
It is advisable to remove the cabin filter before spraying, so the disinfectant can circulate freely. A clogged filter can obstruct airflow and may need replacement, which you can easily do yourself to save money.
Odors can also arise from issues with sunroof drainage. Sunroofs have drainage holes on the sides that can sometimes become blocked, allowing water to seep into the headliner or onto the seats, creating unpleasant smells.
Overall, regular ventilation and keeping the car clean are key steps in preventing unpleasant odors.