What Causes the Air Release Sound in Car AC Every Few Seconds?
3 Answers
Here are the specific reasons why a car's air conditioning system makes an air release sound every few seconds: 1. Throttle valve clogging or sticking: When the AC is turned on, the compressor also starts working. Since the compressor is driven by the engine, turning on the AC increases the engine load. The engine then needs to open the throttle valve wider to allow more air intake. If the throttle valve has carbon buildup or is sticking, it can cause engine vibration and produce abnormal noises. 2. AC pump abnormal noise: There are two main causes for AC pump noise: the electromagnetic clutch and the bearings inside the AC pump. Noise from the electromagnetic clutch is mainly due to wear and tear causing increased clearance, while noise from the AC pump bearings is primarily caused by insufficient lubrication. If not addressed promptly, this can lead to the AC pump burning out, rendering the cooling system inoperable. 3. Improper tension of the compressor drive belt: If the drive belt is too loose, the electromagnetic clutch is prone to slipping. If the drive belt is too tight, it increases the load on the electromagnetic clutch. Improper belt tension can cause abnormal noises in mild cases and damage the AC compressor in severe cases.
A few days ago I encountered a similar issue where the AC made a 'poof' sound every 15 seconds or so, like a fart, making the driving atmosphere a bit awkward. Actually, this is mostly normal operational noise from the car's AC system. During the compressor's start-stop cycle, the solenoid valve frequently opens and closes, causing refrigerant gas flow changes that produce unusual sounds. If the evaporator doesn't drain condensate properly, accumulated water expanding when heated can also create noises. More seriously, there might be air bubbles trapped in the system or insufficient refrigerant, causing unstable pressure and frequent vibrations. I tried adjusting the temperature settings to keep the AC running continuously, which reduced the noise but didn't eliminate it. To be safe, I immediately drove to a repair shop. The professional technician said they needed to check the pipeline seals and top up the refrigerant. Regular maintenance like cleaning the AC filter and evaporator can minimize such issues, as prolonged occurrences waste energy and reduce cooling efficiency.
I have a car that I've driven for several years, and the air conditioning also made this intermittent hissing sound, a 'hiss' every ten seconds or so. I asked a car-savvy friend, and he explained that the cause is usually the compressor clutch repeatedly engaging and disengaging during operation, causing rapid airflow changes that lead to resonance. Alternatively, air bubbles mixed into the refrigerant cycle during compression can create popping sounds. If the evaporator drain is clogged, poor water flow and trapped air can also cause similar noises. From my personal experience: if the sound is slight and cooling is normal, it might just be a minor issue that regular maintenance can improve. But if the frequency increases or is accompanied by strange odors, it could indicate a risk of leaks or blockages in the system. I recommend stopping promptly to check if the cabin air filter is dirty and, if necessary, using professional tools to test the system pressure. Safety comes first—don’t let noise mask potential faults.
