Why does the car air conditioner make a hissing sound when the AC is turned on?
2 Answers
The reasons why the car air conditioner makes a hissing sound when the AC is turned on include: belt slippage, air conditioning compressor failure, or foreign objects in the air duct. More detailed information is as follows: 1. Belt slippage: The air conditioning compressor is driven by the engine crankshaft via a belt. If the belt becomes loose, aged, severely worn, or if the tensioner pulley lacks sufficient tension, it can cause the belt to slip, resulting in a hissing noise. Solution: If the belt slippage is caused by the belt itself, simply replace the belt. If the issue lies with the tensioner pulley, then the tensioner pulley needs to be replaced. 2. Air conditioning compressor failure: When the AC switch is turned on, the air conditioning compressor starts operating. If the compressor is damaged, it may produce a hissing noise. In this case, it is recommended to visit a 4S shop for direct replacement or repair. 3. Foreign objects in the air duct: If there are foreign objects in the air conditioning system's air duct, these objects may rotate repeatedly with the blower's airflow and collide with the air filter, causing a hissing sound. In this situation, you can remove the air filter and carefully inspect and clean any foreign objects in the air duct.
My car used to make a hissing sound whenever I turned on the AC, like there were little insects chirping inside, which was quite annoying. I thought about it myself and suspected there might be leaks in the refrigerant pipes—when the compressor kicks in, the pressure changes and gas escapes, causing the noise. If left unrepaired, the cooling efficiency would drop, and fuel consumption would increase. I’ve checked whether the fan blades or filters were clogged with debris, but usually, that’s not the issue. For safety, it’s best to visit a professional repair shop to detect leaks with specialized tools and fix them promptly to prevent the problem from worsening. During regular car washes, pay extra attention to cleaning the AC components to avoid dust buildup that could accelerate wear. Remember not to disassemble parts recklessly during troubleshooting to avoid damaging other components.
