What is the pressure for charging refrigerant in a car air conditioner?
2 Answers
The low pressure for charging refrigerant in a car air conditioner is 150 to 250 kPa, and the high pressure is 1300 to 1500 kPa. After the refrigerant charging is completed, close the low-pressure manual valve on the manifold pressure gauge, shut off the injection valve on the refrigerant tank, stop the engine, and quickly remove the manifold pressure gauge from the compressor to avoid excessive refrigerant leakage. There are two methods for charging car refrigerant: it can be charged from the high-pressure side or from the low-pressure side. Due to the different states of the refrigerant being charged, the methods vary significantly. Charging from the high-pressure side involves liquid refrigerant, which is suitable for the initial charging after leak detection and vacuuming. Note that this method requires the engine to be stopped, and the refrigerant tank must be inverted. The other method involves charging gas from the low-pressure side, which is slower and is typically used for supplementing refrigerant.
I've been repairing cars for over a decade, and the pressure for AC refrigerant recharge isn't a fixed number. The AC system generally has high and low pressure sides—low pressure typically ranges between 25 to 45 PSI, while high pressure is around 200 to 250 PSI. But this depends on the vehicle—higher ambient temperatures increase pressure, and refrigerant types like R134a also play a role. I often hear car owners complain about weak AC, and improper pressure is usually the main culprit. Before recharging, you need to start the engine, turn the AC fan to the highest setting, and measure with a professional dual-port gauge. Excessive pressure can damage the compressor, while insufficient pressure leads to poor cooling. It's best to get it checked at a professional shop. Regular maintenance, including cleaning the condenser and checking for leaks, can prevent pressure issues—saving money and ensuring safety.
