What causes the hissing sound when the car's air conditioning is turned on?
2 Answers
The hissing sound when the car's air conditioning is turned on may be caused by damaged blower fan blades or foreign objects. Here are some relevant introductions about car air conditioning maintenance: 1. Comprehensive inspection of the air conditioning: When using the air conditioning for the first time, you should first check the air conditioning system, such as checking the refrigerant and whether the air filter is too dirty through the liquid storage tank, and whether there are foreign objects in the radiator; 2. Replace the filter: Pay attention to the cleaning of the air conditioning and regularly replace the air conditioning filter. 3. Maintenance of the car air conditioning liquid storage tank: The liquid storage tank should be replaced in time after two years of normal use, and a new liquid storage tank needs to be replaced every time the pipeline is disassembled for repair or cleaning.
Last time I took my old ride to the repair shop for the same issue, the mechanic said the screeching noise like nails on a chalkboard that gives you goosebumps is usually caused by a worn-out AC compressor bearing. It could also be refrigerant line leaks or a clogged expansion valve, where high-pressure gas escapes through gaps creating that sound. If the noise only happens when AC is on and disappears when turned off, it's almost certainly an issue with the refrigeration system. The mechanic taught me a quick diagnostic trick: after parking, feel the AC low-pressure line for frost buildup - if present, it indicates overcharged refrigerant or expansion valve malfunction. But ultimately, you'll need pressure gauge tests for confirmation. I ended up replacing the compressor (along with the receiver-drier) which cost me around two grand before the noise was finally gone.
