Why is the Mercedes-Benz AC not cooling when turned on?

[StevenFitz]

Mercedes-Benz AC not cooling when turned on may be due to the following reasons: 1. Damaged air conditioning flap. This is relatively rare and located in the middle-lower part of the dashboard. If damaged, it must be replaced. 2. Dirty condenser. A dirty condenser reduces AC heat dissipation, leading to poor cooling performance, so regular cleaning is necessary. 3. Damaged AC compressor, throttle valve, or expansion valve. The compressor is less likely to fail, but faults in the throttle valve or expansion valve can cause poor AC performance, requiring repair at a 4S shop. 4. Aged or loose compressor drive belt. The refrigerant relies on the moving parts of the AC compressor, and a loose drive belt can cause the compressor to slip. Check the engine belt if the AC is not working properly. 5. Low refrigerant level. Car AC systems typically need a refrigerant refill every two to three years. Even with sealed components, refrigerant can slowly leak. Leaks in the AC pipes or condenser can also lead to refrigerant loss.

[McKimberly]

I've handled quite a few cases of Mercedes-Benz AC not cooling when the AC is on. The reasons can vary: the most common is refrigerant leakage, requiring a system pressure check; or the compressor may be faulty, with no cooling effect if there's no sound when starting. It could also be poor condenser heat dissipation due to dust or leaves blocking the fan blades. Additionally, don't overlook the electrical parts, such as a blown fuse or loose circuit connections, which can be easily identified with a multimeter. I recommend doing a simple self-diagnosis first by listening for the sound of the compressor pulley turning after starting the car; if there's no response, check the corresponding position in the fuse box. But if you're not comfortable doing it yourself, don't force it—Mercedes high-end cars are very sophisticated, and taking them to a professional shop for tool-based testing is the most reliable. Regular maintenance can prevent major issues, just adding refrigerant and cleaning the condenser before summer each year will do.

[Jason]

A few days ago, while driving my Mercedes-Benz, I also encountered an issue where the AC wasn't cooling—only blowing hot air on a scorching day, which was really uncomfortable. First, I did a self-check on the settings: I lowered the temperature, but it didn't get cooler. Then, I checked if the air filter was clogged, affecting airflow, but cleaning it didn’t help. A friend suggested it might be due to low refrigerant or a faulty compressor, so I took it to the repair shop. The technician found a minor leak in the system, recharged the refrigerant, and it worked fine again. Now I understand the importance of preventive measures—regularly replacing filters and avoiding prolonged use of recirculation mode can extend the AC's lifespan. Fixing Mercedes-Benz AC issues early saves money and hassle; don’t wait until the problem worsens and affects driving comfort. Such seasonal issues are common, and timely action is key.

[SanBarrett]

I have some interest in car maintenance and came across the issue of Mercedes-Benz AC not cooling. Here's a simple self-check: After starting the engine, turn on the AC and feel if the low-pressure pipe is cold; if it's still warm, try resetting the AC fuse in the fuse box. A dirty condenser is also common, cleaning surface debris might help. I once caused trouble by randomly adding refrigerant, so I advise against risky DIY attempts, as Mercedes-Benz cars have complex electronic systems prone to errors. Professional inspection is more reliable.