What is the normal pressure for adding refrigerant to a car?
2 Answers
Standard refrigerant pressure for car air conditioning: 1. When the compressor is running at 1500-2000 rpm, the high pressure (discharge pressure) should be around 1.5-2.0 MPa, and the low pressure (suction pressure) should be around 0.15-0.35 MPa under normal conditions. The exact values depend on the specific vehicle's air conditioning system configuration and ambient temperature. 2. At idle speed (engine 700-900 rpm), if the ambient temperature is high, such as under direct summer sunlight, the high pressure may be slightly higher, reaching up to about 2.5-2.8 MPa, but generally should not exceed 3.1 MPa. Introduction to car air conditioning refrigerant pressure: 1. The so-called car air conditioning refrigerant is commonly known as Freon, also referred to as "refrigerant" or "coolant" in the market, which is divided into environmentally friendly types (R134a) and non-environmentally friendly types (mainly F12). 2. The refrigerant pressure gauge, also known as a refrigerant meter or Freon gauge, is used to measure the current pressure of the refrigeration system. It is mainly used to detect the pressure values of the refrigerant at different stages of the system, allowing operators to understand the operating condition of the equipment. Currently, the accuracy requirement for refrigerant pressure gauges in China is to reach 2.5 grade.
I've been driving for so many years, what should the refrigerant pressure gauge readings be for the AC? The normal low pressure is between 25 to 45 psi, and the high pressure should be around 150 to 200 psi. When temperatures are high, like 35°C in summer, the low pressure might rise to 40-50 psi, and if the high pressure exceeds 220 psi, you should check for issues. Unstable pressure can cause the AC to blow warm air and increase fuel consumption, affecting performance. Last time my car had a recurring issue with low pressure—only around 20 psi—and after inspection, it turned out the compressor was leaking. After fixing it and recharging the refrigerant to 35 psi, it worked fine. When adding refrigerant, remember to keep the engine running, set the AC to max cooling with the highest fan speed, and use a dual-gauge tool to monitor and adjust slowly—don’t rush. If the low pressure is too high, the system might be clogged; if it’s too low, there’s likely a leak. Minor adjustments are normal due to environmental changes. Regular AC maintenance ensures comfort and safety while driving.
