Why is one of the car air conditioning vents not blowing air?
3 Answers
If one of the car air conditioning vents is not blowing air, it is most likely due to a damaged blower motor. Below is relevant information about car air conditioning: 1. Usage Period: Car air conditioning is an important comfort feature in vehicles, and it is used almost daily during winter or summer driving. 2. Cooling Principle: When the car air conditioning is in cooling mode, the compressor clutch engages, causing the engine to drive the compressor. The compressor then continuously compresses the refrigerant and delivers it to the evaporator. Inside the evaporator, the refrigerant expands and absorbs heat, cooling the evaporator. The cooled evaporator then cools the air blown by the blower. 3. Heating Principle: When the car air conditioning is in heating mode, the engine's high-temperature coolant flows through the heater core. At the same time, the air blown by the blower also passes through the heater core, allowing the air conditioning vents to blow warm air.
I just had my car serviced and noticed there's no air coming from the right rear vent. The mechanic said it's because the air duct flap is stuck. There are small flaps in the car's air conditioning ducts that adjust the airflow direction. If they get stuck due to debris or mechanical failure, the air can't pass through. Another possibility is a dirty cabin air filter blocking the air intake, which can also cause no airflow in the rear seats. My car had this issue last year, and replacing the filter fixed it immediately. It could also be a faulty blower motor resistor, causing no airflow at certain speeds. You can try increasing the fan speed to listen for the blower sound—if you hear a whooshing noise from the rear ducts at the highest setting but still no air, it's likely an air leak. Since it's hot now, this issue needs to be fixed ASAP, or the rear passengers will be sweltering.
Last time, my friend's car's central air vent suddenly stopped blowing cold air, and it turned out the blend door actuator was broken. This flap controls the mix ratio of hot and cold air; if it gets stuck in the hot air position, it blows hot air. To check this, you need to dismantle the center console. It's recommended to first try switching between cold and hot air modes—if the temperature knob completely fails to respond, then this might be the issue. Another possibility is the evaporator freezing up, which can block the air ducts. I've experienced this myself—running the AC at the coldest setting for three hours straight resulted in the airflow gradually decreasing. The solution is oddly mystical—just turn off the engine and wait twenty minutes for the ice to melt. A reminder to everyone: remember to clean the AC ducts regularly, as willow catkins and dust love to settle in the air vents.
