Why does the car air conditioning not cool when the vehicle is not moving?

[MacEmilio]

Here are the main reasons why the car air conditioning does not cool when the vehicle is not moving: 1. Whether the drive belt is broken or loose: If the drive belt is too loose, it will slip, accelerate wear, and fail to transmit power. 2. Internal component damage: Noise inside the compressor may be caused by damaged internal parts, and internal wear can prevent effective compression. 3. Whether the compressor clutch is slipping: A slipping compressor clutch can also cause issues. 4. Insufficient or excessive refrigerant: If a large number of bubbles are seen through the sight glass, it indicates insufficient refrigerant. If water is poured on the condenser to cool it and no bubbles are seen in the sight window, it indicates excessive refrigerant. 5. Refrigerant leakage: Check for oil stains at the connections and seams of each device. Oil stains at the connections or seams indicate refrigerant leakage, and the relevant parts should be tightened or replaced.

[Willow]

I've encountered this issue several times, most commonly when the condenser fan fails. When the car isn't moving, there's no natural airflow for cooling, so the fan is responsible for blowing air over the condenser to help cool the refrigerant. If the fan is stuck or the fuse is blown, the cooling efficiency drops, and the AC will definitely underperform. Try starting the car and turning on the AC, then step out to listen for a humming sound from the engine compartment fan. If there's no noise, it might be a faulty motor or relay problem. Regularly cleaning dust and debris under the hood can also prevent fan failures. Don't delay repairs in summer – get it fixed promptly to avoid sweating through uncomfortable drives.

[VanGia]

Electrical system issues are another major concern, especially voltage fluctuations during idle. For example, poor contact in the compressor relay or sensor misjudgment can interrupt the air conditioning control signal, causing the compressor to stop working. Once the compressor stops, the cold air supply is cut off. Check the air conditioning indicator on the dashboard yourself—if it's lit but there's no cold air, it's likely the relay has failed. Sometimes replacing a small component can fix the issue, but if you're not knowledgeable, it's best to visit a professional shop to test the circuit to avoid causing a short circuit through improper repairs. Paying attention to whether the fan is running when the air conditioning is on can also help diagnose electrical faults.

[EllieMarie]

Insufficient refrigerant or leaks can cause the air conditioning to fail more noticeably when the car is parked. While moving, the refrigerant circulates faster and may still work somewhat, but when stopped, the lack of pressure leads to poor evaporation. A hissing sound from the AC system usually indicates a leak point. DIY repairs are not feasible; take the car to a professional shop to test the pressure and recharge the refrigerant. Maintain a well-sealed system and schedule a check-up every two years to prevent leaks in older vehicles.