What causes high low pressure and low high pressure in car air conditioning, resulting in no cooling?
4 Answers
Car air conditioning, high low pressure, low high pressure, no cooling causes and solutions: 1. Insufficient refrigerant in the compressor: Add refrigerant. 2. Sensor failure: If a certain temperature zone is not cooling, such as the refrigerator compartment or variable temperature compartment, check whether the sensor parameters of that temperature zone are normal. 3. The solenoid valve does not reverse: Check whether the solenoid valve is normal according to the solenoid valve detection method. 4. Capillary tube blockage: If a certain temperature zone is not cooling and the solenoid valve reverses normally, it can be determined that it is a system problem, and further system opening is required for judgment. 5. System failure: Check whether the capillary tube is dirty, oil clogged or ice clogged. If the refrigerator sometimes cools and sometimes does not, it is generally ice clogged. If nitrogen is used to blow the pipeline and dirt or blockage is found, it indicates dirty or oil clogged. If there is no refrigerant when opening the system, it indicates refrigerant leakage. Check the leakage point for repair. 6. Compressor failure: The whole machine does not cool. Open the system and check whether there is enough refrigerant sprayed out to determine whether it is refrigerant leakage. If there is no leakage, check whether the compressor is not exhausting.
I often repair air conditioning systems, and when I see high low pressure and low high pressure without cooling, it's mostly a compressor issue. The compressor is responsible for compressing the refrigerant. If it's worn or has internal leaks, the refrigerant can't be compressed properly, causing the high-pressure side to drop and the low-pressure side to rise. Another possibility is a clogged expansion valve, which disrupts refrigerant flow and causes an imbalance between high and low pressures. Sometimes, insufficient refrigerant or air in the system can also disrupt the cycle. This directly affects cooling performance, causing the AC system to fail. I recommend car owners first check the compressor for unusual noises and inspect the expansion valve for dirt. Regular maintenance can prevent such issues, like checking the refrigerant system every two years. If you encounter this problem, don’t try to fix it yourself—it’s easy to damage components. Instead, take your car to a professional repair shop for a proper diagnosis. Safety first.
I'm a car owner, and my air conditioning had the same issue last year—low pressure was too high while high pressure was too low, and the cooling just stopped working. I was really scared at the time because I didn't understand what was happening. Later, I was told it might be a faulty compressor or a stuck expansion valve. If the compressor is worn out due to aging, it can't compress the refrigerant properly, so the high pressure won't rise, while the low pressure remains relatively high. A clogged expansion valve is even worse—if the coolant can't flow, it can't dissipate heat. I also suspected there might be a refrigerant leak or moisture in the system. My advice is to start with the simplest checks: see if the external cooling fan is running and if the cabin air filter is dirty. If that doesn't solve it, better call a mechanic—safety comes first. When using the AC, avoid turning it on when the car is scorching hot, and make sure to get regular maintenance. Don't delay fixing this issue—poor cooling can affect driving visibility.
I'm interested in automotive technology. This kind of high and low pressure abnormality leading to no cooling is usually caused by inefficient compressor or expansion valve failure. If the compressor doesn't compress the refrigerant, the high and low pressure will be unbalanced, with low high pressure and high low pressure. A clogged expansion valve interrupts the flow, causing the refrigeration cycle to fail. Air in the system or insufficient refrigerant can also cause this. During inspection, you can check the compressor oil level and ensure the valves are clean. Proper maintenance can extend its lifespan. In short, seek professional help quickly.
