What Causes High Low Pressure in Car Air Conditioning and How to Fix It?
2 Answers
High low pressure in car air conditioning is a compressor malfunction. If the pressure gauge shows this phenomenon, and there is no shortage of refrigerant in the pipeline, but the air conditioning performance is poor, then the issue may lie with the air conditioning compressor. There could be internal leakage in the compressor, and generally, replacing the compressor can resolve the problem. Below are the functions of car air conditioning: 1. Temperature Regulation: This is the primary function of car air conditioning. In summer, the cooling system produces cold air to lower the temperature inside the cabin; in winter, except for large commercial vehicles that use independent combustion heaters for warmth, other vehicles mostly utilize the vehicle's residual heat for heating. 2. Humidity Regulation: Humidity significantly affects the comfort of passengers inside the cabin. The humidity inside the cabin should generally be maintained between 30% and 70%. Standard car air conditioning systems do not have the capability to regulate cabin humidity; only through the use of ventilation systems or advanced luxury cars equipped with integrated heating and cooling systems can this be achieved. 3. Airflow Regulation: The velocity and direction of airflow greatly influence passenger comfort. If air is blowing directly, the velocity should be limited to a certain range when the temperature is appropriate. The airflow velocity can be adjusted based on passengers' living environment, age, health condition, and temperature preferences. 4. Air Purification: The quality of air inside the cabin is crucial for ensuring comfort.
When I was commuting in my old Accord, I noticed the AC wasn't cooling. The mechanic diagnosed it as high low-side pressure. The cause was overcharging of refrigerant—it was overfilled during the last maintenance to save money, causing excessive system pressure. Alternatively, the condenser might be clogged with dirt, leading to poor heat dissipation in summer when the fan isn't running. Also, if the expansion valve is stuck and doesn't close properly, it can cause the low-side pressure to rise. The solution is simple: first, use a pressure gauge to check the low-side pressure. If it's high, remove the excess refrigerant and clean the condenser and fan blades with water. Don't try to fix it yourself—damaging the compressor would be more expensive. Remember to maintain your AC regularly, especially checking the refrigerant level before hot weather. After that repair, the cold air came back instantly, making driving much more comfortable.
