Is It Normal for a Car Air Conditioner to Have High Low Pressure and Low High Pressure?
3 Answers
It is not normal for a car air conditioner to have high low pressure and low high pressure. The reasons are: 1. Faulty or damaged air conditioner expansion valve; 2. The compressor displacement does not meet the requirements. The solutions for high low pressure and low high pressure in a car air conditioner are: 1. Replace the dust filter; 2. Inspect and replace the air conditioner expansion valve; 3. Clean the radiator and condenser. A car air conditioner refers to the air conditioning device installed in a car, which consists of a compressor, an electronically controlled clutch, a condenser, an evaporator, an expansion valve, a liquid storage dryer, pipes, a condenser fan, a vacuum solenoid valve, an idle speed controller, and a control system. Its functions are: 1. To cool, heat, ventilate, and purify the air inside the cabin; 2. To provide a comfortable riding environment for passengers, reduce the driver's fatigue, and improve driving safety.
I've been repairing cars for over 20 years, and most cases of high low pressure and low high pressure in car air conditioning systems indicate abnormalities. This situation commonly occurs due to insufficient refrigerant or a stuck expansion valve opening too wide, causing pressure imbalance. You'll notice poor cooling performance with no cold air from the vents. When measuring with pressure gauges, normal high pressure should be between 150-250 psi, while low pressure around 25-45 psi. If low pressure exceeds 50 psi and high pressure drops below 100 psi, it's serious. Worn compressors or internal leaks can also cause this, requiring replacement. During inspection, don't forget to check wiring connections and filters to prevent minor leaks from becoming major issues. It's best to perform a simple check before every summer to avoid sudden heat discomfort while driving, which affects safety. Experienced car owners often say such problems should be addressed early, otherwise they'll increase fuel consumption and cost more money.
Last month, the air conditioning in my Volkswagen also had low pressure on the low side and high pressure on the high side, blowing warm air for a long time while driving. I took it to a repair shop, and they said it might be due to a refrigerant leak or an expansion valve issue. They first topped up some R134a gas, and if that doesn't work, parts will need to be replaced. Driving in summer with this issue is really miserable—the car feels like a steamer, and it's easy to get drowsy on the highway. I suggest not trying to fix it yourself; a professional shop can diagnose it quickly. Keep an eye on your AC's performance, like weak cooling or unusual noises, and address issues promptly. If the compressor fails, repairs can be costly—my friend spent over 800 last time. Fixing it early saves money and hassle.
