What is the normal pressure for a car air conditioner?
2 Answers
The normal high pressure for a car air conditioner is between 1.3 and 1.7 MPa, while the low pressure ranges from 0.15 to 0.25 MPa. Below is relevant information: 1. Working principle: The car air conditioning refrigeration system consists of a compressor, condenser, liquid storage dryer, expansion valve, evaporator, and blower. These components are connected by copper (or aluminum) pipes and high-pressure rubber hoses to form a sealed system. When the refrigeration system operates, the refrigerant circulates in different states within this sealed system. Each cycle involves four basic processes: compression, heat dissipation, throttling, and heat absorption. These four processes repeat continuously to achieve the goal of lowering the air temperature around the evaporator. 2. Air conditioning maintenance: In summer, do not immediately activate the internal circulation when entering the car. Instead, first open the windows for ventilation and turn on the external circulation to expel the hot air. Only after the cabin temperature has dropped should you switch to internal circulation. The direction of the air vents should not be adjusted arbitrarily. According to the principle that cold air sinks and hot air rises, the correct approach is to point the vents upward when using the air conditioner and downward when using the heater. Do not leave the air conditioner running for extended periods, as prolonged use can increase the pressure on the condenser, causing wear and tear on the refrigeration system. The air conditioner is already a heavy load on the engine, which itself is a heat source, especially in hot weather. Do not turn off the engine before turning off the air conditioner, as this will cause the engine to start with the air conditioner's load during the next ignition, potentially damaging the engine. Therefore, always turn off the air conditioner before shutting down the engine, and wait two to three minutes after starting the car for the engine to be properly lubricated before turning on the air conditioner.
From my years of car repair experience, normal car AC pressure depends on both the high and low pressure sides: the low pressure is typically between 25 to 40 psi, while the high pressure ranges around 200 to 250 psi. However, these aren't absolute numbers and vary with temperature—for example, in summer heat, the high pressure can spike to 270 psi without being unusual. Low pressure that's too low may indicate leaks or compressor issues; excessively high pressure can damage the system. When I check with a pressure gauge, I first let the engine run for a few minutes with the AC set to maximum cooling and fan speed to get accurate readings. R134a is a common refrigerant, but switching to other types alters the pressure range. The key is regular checks—if readings deviate significantly, seek professional repair. High-pressure systems are dangerous if mishandled, so avoid DIY fixes.
