Why can I hear water sounds when the car's air conditioning is on?
4 Answers
Hearing water sounds when the car's air conditioning is on is caused by water passing through the heater core. Check if the engine coolant is low. In this situation, you can first add antifreeze, then press the accelerator pedal twice to let the engine run at high speed, which helps expel air from the system. The car air conditioning system is designed to regulate and control the temperature, humidity, air cleanliness, and airflow inside the vehicle cabin, providing a comfortable environment for passengers and reducing travel fatigue. A car air conditioning system generally consists of components such as the compressor, electronically controlled clutch, condenser, evaporator, expansion valve, receiver-drier, pipelines, condenser fan, vacuum solenoid valve, idle speed controller, and control system.
I just went to the 4S dealership to fix this issue recently. The gurgling water sound when the AC is on is most likely caused by incomplete drainage of the AC condensate. The drain pipe under the car is either clogged or bent, causing water to accumulate in the evaporator. When the blower runs, it sloshes the water around, making noise. The sound is especially noticeable when parked on a slope or during braking. You can fix it yourself by using a wire to unclog the black rubber drain pipe under the chassis, located below the passenger side. If the drain pipe isn't clogged but the sound persists, check if the cabin air filter is soaked and damaged. If it's soaked, you'll need to replace the whole set, otherwise it will mold.
There's also a gurgling sound in my car. After the mechanic removed the glove compartment and checked, they said it was due to condensed water flowing back into the blower. Normally, the air conditioning produces vapor when cooling, which is drained outside through a dedicated tube. However, if the drainage tube is positioned higher than the evaporator, or if the car is parked under trees for a long time, the drainage hole can get clogged with fallen leaves, preventing water from draining and causing it to slosh around in the plastic pipes. This is especially noticeable right after turning off the air conditioning, sounding like dripping water from an unsecured pipe. To locate the drainage tube, open the hood while parked, have someone turn on the air conditioning inside the car, and crouch at the front of the car to listen for the dripping sound.
I've handled many such cases in my repair shop. There are mainly two reasons for hearing water flow sounds: one is the refrigerant flowing through the pipes, especially in new cars or right after refrigerant recharge, which is a normal physical phenomenon. The other is a clogged drain pipe, where water accumulates in the drain pan, causing a gurgling sound when the fan operates. If you also detect a musty smell, it's almost certainly a complete blockage. Here's a lesser-known fact: prolonged use of the recirculation mode can cause the evaporator to frost up, and the defrosting process may also produce water sounds. It's recommended to occasionally switch to fresh air mode.
