What Causes High Low Pressure in Car Air Conditioning and How to Fix It?

[TuckerLee]

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.

[StEmerson]

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.

[VanJasmine]

I work in auto repair and often encounter high low-pressure issues. Most of the time, it's due to excessive refrigerant—poor control during refilling; the condenser fins are too dirty, blocking the airflow; the fan motor isn't working, causing poor heat dissipation; or the expansion valve is stuck. For diagnosis, you need to use a specialized gauge to measure the low-pressure line. If it's high, troubleshoot step by step—first check if the refrigerant is overfilled (remove excess if needed), then clean the condenser by blowing out dirt with compressed air, and verify if the fan is spinning properly. If the issue persists, try replacing the expansion valve. I advise car owners not to delay—high low-pressure affects AC efficiency and increases fuel consumption. Getting it fixed early at a professional shop saves trouble. I’ve tried DIY fixes myself, but mistakes like refrigerant leaks make things worse. Professional tools are the way to go.

[VonXavier]

Recently noticed the car's AC low pressure is too high. Checking the mobile app records suggests it might be due to excessive refrigerant or a dusty condenser. Poor cooling from a faulty fan can also cause this. The reasons are simple, but a visit to the repair shop for pressure gauge testing is necessary. The solution is to have the technician reduce the refrigerant level, clean the front condenser to ensure proper ventilation, and repair the fan if it's faulty. Don't delay too long, or the compressor will wear out, making summer drives miserable. My little Civic was restored to like-new condition after the last repair, making it much more reliable. Remember, avoid adding refrigerant yourself to prevent mistakes.