What Causes Uneven Airflow in Car Air Conditioning?
3 Answers
Uneven airflow, where one side has stronger airflow than the other, may be caused by the evaporator on one side icing up. Here are some precautions for using car air conditioning: 1. Turn off A/C during startup and rapid acceleration: Since the air conditioning (non-independent type) consumes some engine power when turned on, it's best to turn off the A/C during vehicle startup and rapid acceleration, and then turn it on after the vehicle is moving. This prevents insufficient engine power during acceleration and startup while also saving fuel. 2. Avoid setting the air conditioning temperature too low: Many drivers prefer setting the temperature very low in summer, thinking it's more comfortable. However, this is a misconception because excessive temperature differences between inside and outside the car can easily lead to the driver catching a cold. Additionally, excessively low temperatures may increase the risk of arthritis for passengers. Normally, the cabin temperature should be 5°C to 6°C different from the outside temperature. 3. Adjust the air vent direction: Based on the principle that cold air sinks and hot air rises, when using the air conditioning, set the vents upward when cooling and downward when heating.
When I encounter this issue, it's mostly due to the small switch in the air conditioning damper getting stuck, possibly from aging or dust buildup, causing incomplete opening/closing on one side. Another possibility is debris blockage in the air vent ducts, like leaves or small insects, leading to uneven airflow. Sometimes a dirty filter can also cause this by restricting air circulation. I usually start by checking the filter myself - cleaning or replacing it often helps significantly. But if the problem persists, it's best to visit a repair shop to inspect the damper actuator. Additionally, this affects cabin temperature distribution, making long drives uncomfortable with one side cold and the other hot.
My car had a similar issue before, feeling weaker airflow on the left side than the right. The main causes could be an unbalanced diverter in the ducts or a loose temperature control linkage. A dirty air filter is also common—I clean mine monthly and it rarely happens now. Recently I noticed improper AC mode selection, like using only external circulation without proper adjustment, can cause uneven airflow. This makes defogging windows difficult during night driving, creating dangerous visibility issues. So address it promptly—try replacing the filter yourself first, if that doesn't work, have a professional check the electronic control components.
