What Causes the Unpleasant Odor When Turning on the Car Air Conditioning?

[LaJoy]

Car air conditioning may emit an unpleasant odor due to prolonged failure to replace the air filter, uncleaned evaporator box, or foreign objects in the ventilation ducts. Failure to Replace the Air Filter: If the filter is not cleaned or replaced for an extended period, it can accumulate significant dust and debris, leading to odor emission. Foreign Objects in Ventilation Ducts: If the car has not been used for some time, small insects or other animals may enter the ventilation ducts. Additionally, if the habit of using the external circulation mode during high-speed driving exists, numerous insects might collide into the ducts. Over time, these foreign objects and dust in the ducts can produce unpleasant smells. Uncleaned Evaporator Box: While most impurities filtered by the evaporator box are expelled through the air conditioning drain pipe, some may mix with condensed water and remain on the evaporator's surface, fostering mold growth and resulting in odors. Solutions for Unpleasant Odor When Using Car Air Conditioning: Check the Air Filter: The car air filter is typically located behind the glove compartment on the passenger side. Some models allow removal of the glove compartment panel by pressing inward, while others may require simple tools. Once the glove compartment is removed, the air filter becomes visible. If the filter appears dirty, replace it by removing the old one and installing the new filter in the same manner. Clean Ventilation Ducts: Turn the air conditioning system to maximum airflow, turn off the AC button, switch to external circulation, and spray air conditioning cleaner directly into the air filter. After spraying the required amount, keep the car doors open and let the system run for a while. Performing this under direct sunlight is recommended, as heat and UV rays provide additional sterilization. Seek Professional Deep Cleaning: If the odor persists, the issue may stem from excessively dirty ventilation ducts or evaporator box, which cannot be resolved with simple cleaning. Since certain areas of the ducts and the evaporator box are difficult to access with standard tools, professional auto repair shops may need specialized equipment like endoscopes for thorough cleaning. Therefore, it is advisable to visit a 4S shop or repair center for comprehensive maintenance to fully resolve the issue.