What is the reason why the AC cannot be turned on?

[VonAustin]

AC stands for the activation of the compressor, which is used for cooling. If the compressor is not turned on, only the fan will start. If the compressor can be activated but the AC switch cannot be turned on, then the AC indicator light is likely damaged. Here are the letter markings on the car air conditioning system: 1. AC: The A/C button is the switch for the air conditioning compressor. Only when the compressor is turned on can the air conditioning provide cooling. When the A/C light is on, it means the compressor is working, and the car's air conditioning can cool. 2. MAX: When the MAX function is activated, the car's air conditioning will operate at full capacity, with the fan at maximum speed. This function is only available in some models with automatic air conditioning. Pressing MAX will make the air conditioning compressor and fan use maximum output to quickly reach the set temperature. 3. FRONT button: This is the front window defrost switch. When turned on, the air vent will blow air toward the front windshield. 4. REAR button: This is the rear window defrost switch. When turned on, the rear windshield's electric heating wire will heat up.

[McJocelyn]

As an experienced driver, I once had a situation in summer where the car's air conditioning suddenly stopped working, making the interior unbearably hot. There can be several reasons for this: the most common is refrigerant leakage, which prevents the compressor from starting; or a blown fuse, which can usually be checked in the fuse box near the dashboard. It could also be a faulty button or poor wiring contact. Additionally, if there's a fault code in the air conditioning system, the car's computer might automatically shut it off to prevent damage. I recommend first trying to restart the vehicle and checking if the air conditioning button is turned on. If that doesn't work, take it to a repair shop to check the refrigerant pressure and wiring. Regular maintenance of the air conditioning system is crucial to prevent leaks and electrical issues, ensuring comfort and safety. Especially before long-distance drives, making sure the air conditioning is working properly can help avoid the risk of heatstroke.

[StTucker]

For enthusiasts like us who love tinkering with cars, an AC not turning on can be caused by various issues. Electrical problems are common, such as a blown fuse or a failed relay preventing current from reaching the compressor. The compressor itself might be stuck or the clutch may not engage. Insufficient refrigerant can also cause the system to shut down. I've also encountered faulty temperature sensors where the computer misreads the cabin temperature and shuts off the AC. The troubleshooting process is straightforward: use a multimeter to check if the fuse is intact, and listen for a humming sound when the compressor starts. Preventive measures include avoiding excessive AC use, not parking in direct sunlight during summer to reduce system load. If you're not familiar with electrical circuits, it's best not to attempt repairs yourself—consult a professional technician to diagnose the issue with a scan tool.

[DelCorey]

It's really annoying when the car air conditioning suddenly fails during family trips, with kids complaining about the heat inside. Common causes include worn-out AC switch buttons malfunctioning or incorrect mode settings, such as selecting fan-only mode without activating cooling. Another possibility is the AC not working when the battery charge is low. A clogged filter affecting airflow may also be the culprit, manifesting as no cold air output. It's recommended to first adjust the temperature knob and ensure the recirculation mode is on. If that doesn't help, check the fuse box yourself or visit a repair shop for system cleaning. Testing the AC before driving can prevent on-road troubles, ensuring a comfortable journey that keeps the whole family happy.