What are the reasons why the car air conditioner is not cooling?
5 Answers
The reasons why the car air conditioner is not cooling are: 1. Lack of refrigerant; 2. Damage to the air conditioner flap; 3. Loose drive belt of the car air conditioner compressor; 4. Blockage of the air filter and filter screen; 5. Moisture infiltration into the refrigeration system. The functions of the air conditioner: 1. Achieve cooling effect through the continuous cycle of refrigerant; 2. Remove dust, odors, smoke, and toxic gases from the air inside the car, humidify the air inside the car, and increase the relative humidity of the air inside the car; 3. Use engine coolant, waste heat, or heat generated by a burner as a heat source for heating, which is heated by the heater and sent into the car air or outside air by the blower, raising the temperature at the air outlet to achieve the purpose of heating; 4. Draw in fresh external air for ventilation and air exchange, which also plays a good role in preventing windshield fogging.
Last time I had my car repaired, I discussed this issue with the mechanic and found that the most common cause of weak air conditioning is insufficient refrigerant, commonly known as a refrigerant leak. If your car hasn't had its refrigerant replaced in five or six years, this is likely the problem. A loose compressor belt or a clogged cabin air filter can also prevent cold air from coming out, especially in older vehicles. Another often-overlooked cause is when the condenser fins get clogged with dust or pollen—this component is located at the front of the car and needs regular cleaning. I recommend first checking the cabin air filter, which is located behind the glove compartment on the passenger side; you can replace it yourself. If none of these fixes work, the issue might be with the evaporator or expansion valve, and it's best to visit a shop for a precise diagnosis using a pressure gauge.
As an automotive engineer, I frequently receive complaints about air conditioning systems. Sudden loss of cooling in the AC system typically has three possible causes: First, refrigerant leakage—aging connection pipes or sealing rings can lead to loss of refrigerant. Second, compressor malfunction—slipping electromagnetic clutches or internal wear can reduce cooling efficiency. Third, faults in the AC control system, such as failed temperature sensors or stuck air flap motors. A special reminder for drivers who frequently use recirculation mode: condenser frosting can also diminish cooling performance. The most reliable approach is to first use a diagnostic tool to read the AC system's data stream, observing high and low pressure values and temperature sensor feedback—this is far wiser than blindly recharging the refrigerant. If the pressure gauge shows both high and low pressures are elevated, it often indicates poor condenser heat dissipation or issues with the cooling fan.
Last week, I just dealt with my car's air conditioning issue. Initially, I noticed the airflow had weakened, and later it stopped cooling altogether. The mechanic checked four key points for me: first, the cabin air filter, which was indeed clogged with leaves; then, the refrigerant pressure was tested and found to be below the standard level, requiring a top-up; next, the compressor belt was inspected, and its aging had caused slipping and insufficient rotation speed; finally, the electric fan was checked to ensure it was functioning properly. The entire diagnosis took just twenty minutes. Now, I clean the condenser every quarter and check the refrigerant oil level monthly, which has significantly improved the AC performance. Remember, air conditioning systems that go unused for long periods are prone to issues—it's best to run them for at least ten minutes each month.
The worst fear when driving in summer is the air conditioning breaking down. Here's how I handled it last time: first, feel the temperature of the AC pipes—the low-pressure pipe should be cool and the high-pressure pipe hot for normal operation. Then, listen for the compressor's working sound; if there's no obvious engagement noise, the clutch might be burned out. For regular family cars, it's recommended to refill the refrigerant every five years, and older cars need extra attention to pipe sealing. Recently, I helped a neighbor fix a case where modified lighting accidentally damaged the AC wiring, highlighting the risks of unauthorized modifications. When the AC suddenly stops cooling, avoid immediately turning the fan to maximum speed, as this can easily burn out the resistor. Since the start of the hottest summer period, 40% of AC repairs are due to cooling issues, especially the buildup of insect debris between the radiator and condenser, which should be checked regularly.
