What Causes the Hissing Sound When Turning on the AC in a Car?
2 Answers
This sound usually occurs when the refrigerant level is low. It's recommended to visit a service station to measure the refrigerant level. Here are some maintenance tips for car air conditioning: 1. Avoid randomly adjusting the air vent direction: Properly adjust the air vents based on the principle that cold air sinks and hot air rises. When using the AC, direct the vents upwards, and when using the heater, direct them downwards. 2. Regularly start the AC during winter: In some regions, the AC may not be needed in winter, but prolonged disuse can cause rubber seals to age and the lubricant on internal components to dry out. Regularly starting the AC ensures proper lubrication and maintains good condition. It's advisable to start the AC once a week during winter. 3. Limit continuous AC usage: Extended use of the AC can increase pressure on the condenser, causing significant wear to the cooling system. Therefore, avoid using the AC for too long at a time. If the cabin temperature is comfortable, turn off the AC for a while before turning it back on later.
When I encounter this issue, I suspect there might be a refrigerant leak in the AC system. It sounds like a hissing airflow noise, right? This usually indicates refrigerant escaping from the pipes, joints, or condenser. My car had the same problem before—I recharged the refrigerant, which lasted a few months before failing again because the leak wasn’t properly fixed. Compressor issues can also cause this, especially in older cars where the compressor is worn out and produces abnormal noises. A faulty expansion valve can similarly create a sound resembling a gas leak, as it controls refrigerant flow. I recommend visiting a professional shop immediately to check with a fluorescent leak detector. Don’t wait until the AC stops cooling entirely—driving in the summer heat would be miserable.
