Why does the car air conditioner emit an odor when starting?

[LeAdriana]

It may be due to mold growth in the air conditioner's evaporator box and ventilation ducts that causes the unpleasant smell. Below is the relevant introduction: 1. Introduction to Car Air Conditioning: It is used to adjust and control the temperature, humidity, air cleanliness, and airflow inside the car cabin to an optimal state, providing a comfortable riding environment for passengers and reducing travel fatigue. It also creates favorable working conditions for the driver and plays a crucial role in ensuring safe driving. Generally, it includes cooling devices, heating devices, and ventilation devices. This integrated system makes full use of the limited space inside the car, featuring a simple structure and ease of operation, making it a popular modern car air conditioning system internationally. 2. Maintenance Methods: Upon reaching their destination, most car owners typically turn off the air conditioner and leave the car immediately. Unlike in autumn and winter, the significant temperature difference between the inside and outside of the car during hot summer months can lead to mold growth in the air conditioning system, fostering mildew. Therefore, car owners should turn off the air conditioning a few minutes before arriving at their destination and switch to natural air mode. This allows the temperature inside the air conditioning ducts to rise, eliminating the temperature difference with the outside environment, thereby maintaining relative dryness in the air conditioning system and preventing mold proliferation.

[StHarley]

When I first bought the car, the AC had a musty smell that was really strong, mainly due to dust and bacteria accumulating in the filter and the small water tank inside the AC system. Over time, it developed mold, especially noticeable during the humid spring and summer seasons. When the AC was off, moisture couldn't escape, and as soon as I turned it on, the weird smell would blow right out. Later, I went to a repair shop to clean the evaporator and replace the filter, and it instantly felt much fresher. I recommend turning off the AC a few minutes before parking to let it blow naturally, which helps reduce water buildup. Also, check the filter regularly—don’t skimp on this cost. Otherwise, you’ll be holding your breath while driving, which is uncomfortable and can even cause sneezing, affecting safety. It’s definitely better than sitting in the car breathing in moldy air.

[McJasmine]

I've experienced this issue a few times. The most common reason for a musty smell when starting the car's AC is either a cabin air filter clogged with dust from not being replaced for too long, or mold growth inside the ducts causing bacterial buildup. Sometimes poor ventilation after prolonged parking can also cause this. Fortunately, I maintain regular maintenance by replacing the filter every six months and doing simple self-cleaning of accessible parts. These odors aren't just unpleasant - they can degrade cabin air quality and cause allergic reactions or nasal congestion. Don't delay addressing it - first check if the filter is dirty, and for professional cleaning, find a reliable auto shop to service the entire system. Driving safety comes first, and fresh air helps maintain focus on road conditions.

[VonAnthony]

A foul smell when turning on the AC may be caused by mold lurking in the filter or internal water tank. High humidity accelerates bacterial growth, and turning on the cold air can blow out harmful particles. This is unhealthy, especially for people with allergies who may experience coughing or inflammation. Early intervention is crucial: replacing the filter can block dust; using specialized disinfectant sprays can eliminate hard-to-reach areas. Remember to ventilate frequently and turn off the AC a few minutes before parking to let moisture dissipate, preventing recurring mold buildup. Small issues left unchecked can lead to bigger problems.