How to Deal with the Sour and Musty Smell in Car Air Conditioning?

3 Answers
VanZoey
07/24/25 8:36am
For a sour and musty smell in the car air conditioning, it is recommended to promptly clean the evaporator (the air conditioning system should generally be cleaned once a year, preferably before the summer season), and also replace the air filter and perform a thorough cleaning of the air conditioning system. Below is a detailed explanation: 1. Possible Causes: The sour smell in car air conditioning may be due to unclean air filters, dirty air ducts, or accumulated dust on a damp evaporator. 2. Hazards of Contaminants and Solutions: (1) A large amount of contaminants and dust can breed various molds harmful to human health. (2) Proper use of the air conditioning system can effectively keep the evaporator dry, reducing the growth of bacteria and mold.
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Hunger
08/11/25 1:15am
I've been driving for over a decade, and when there's a sour smell from the car's air conditioning, it's usually due to mold growth inside, especially around the evaporator because condensation tends to accumulate there. When it's hot and you turn on the AC, that sour smell comes out. I've encountered this several times before. First, I check the cabin air filter—it's like a mesh that filters the air. If it's dirty, I replace it with a new one that matches the car model. It's easy to do it myself. If the filter is clean but the smell persists, I've used AC deodorizing spray before. Just spray a few times into the air intake, turn on the exterior air circulation for a while, and it can kill the mold and remove the odor. If the problem is severe and ongoing, it's best to have professionals clean the evaporator or the entire system—they use equipment to thoroughly clean it. For prevention, I make it a habit to turn off the cooling function a few minutes before shutting off the AC, just running the fan or warm air to dry out the ducts. In summer, I turn on the AC at least once a week, even without cooling, to keep it dry. These methods work well and save you the hassle and expense.
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KevinLee
09/25/25 2:18am
I'm a new driver, and the sour smell from the air conditioner is really uncomfortable, giving me a headache when I smell it. After some research, I found that this odor is mostly caused by moldy substances inside the AC system, such as water stains in the evaporator or ducts that have grown bacteria. When I first encountered this issue, I checked if the cabin air filter was dirty. The filter is usually located near the glove compartment, and replacing it can often help reduce the smell a bit. However, the more reliable solution is to take the car to a 4S shop or repair shop and have them professionally clean the ducts with specialized equipment, ensuring a thorough and safe cleaning. To prevent this, avoid smoking in the car or leaving moldy items inside, and don't let the AC sit idle—run it occasionally to ventilate and dry the system. If the odor persists, it might indicate a leak in battery-related components, which can be identified through professional testing. In short, don't tough it out—address the issue early to ensure health and peace of mind while driving.
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