What Causes the Sour and Pungent Smell When the Car Air Conditioner is On?
2 Answers
If the condensed water in the evaporator is not drained in time, bacteria can produce toxins, leading to a sour and foul odor. Below is an introduction to the parts of the air conditioning system that are prone to producing odors: 1. Odor from the cabin air filter: The cabin air filter is responsible for filtering the air entering the car and can accumulate a large amount of dust and debris. 2. Odor from the air conditioning evaporator: The air conditioning evaporator, shaped like thick aluminum fins, can also collect dust. After using the air conditioner, the evaporator, being a component where hot and cold air exchange, accumulates moisture from condensation, which can lead to mold growth and a musty smell. 3. Odor from the air conditioning ducts: The air conditioning ducts are another area where dust accumulates. The delivery of cold air can cause moisture to form in the ducts, resulting in mold growth and a musty odor.
I've also encountered that sour, pungent smell from the air vents when driving my sedan, which strongly resembles the odor of rotten vegetables - quite annoying. The main cause is excessive moisture on the evaporator surface, especially during summer when AC is used frequently. If condensation doesn't dry completely, it easily breeds mold or bacteria. These microorganisms thrive in damp environments and produce acidic metabolic byproducts, hence the irritating odor when air blows out. The solution isn't complicated - I've tried these methods myself: After parking, turn off the AC but let the fan run for a few minutes to dry the system; replace cabin air filters regularly to reduce dust accumulation; if needed, use specialized cleaning sprays through the vents. For persistent odors, professional evaporator deep-cleaning at a repair shop is recommended to prevent respiratory discomfort. Regularly using fresh air mode improves circulation and prevents the car from becoming a bacteria breeding ground. While this seems minor, prolonged exposure may affect nasal/throat health - early treatment brings peace of mind.
