Should You Charge the Low or High Pressure Side First When Adding Refrigerant to a Car AC?
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When adding refrigerant to a car AC, start with the low-pressure side because the system is vacuumed, and the high-pressure side retains an interface only suitable for adding refrigerant. This approach is chosen based on the different substances being added. Precautions for Adding Refrigerant to a Car AC: Before adding refrigerant, use a pressure/vacuum machine to pressurize the system and check for leaks. If leaks are found, inspect all AC system components, including pipe joints, condensers, evaporators, dryer bottles, compressors, etc., by spraying soapy water to locate the leaks. Address or replace the faulty parts. After replacement, pressurize the system again to check for leaks. Only proceed with vacuuming and adding refrigerant once no leaks are confirmed. Steps for Adding Refrigerant: Connect the refrigerant gauge to the AC system (both high and low-pressure pipes) and vacuum the system. Select the low-pressure side for vacuuming (turn the switch corresponding to the low-pressure gauge counterclockwise, ensuring the high-pressure gauge switch remains closed). Generally, there's no need to monitor the negative pressure value; 3 minutes of vacuuming is sufficient. After the time elapses, tighten the low-pressure gauge switch, then connect the refrigerant canister for filling (keeping the high-pressure switch closed and only opening the low-pressure switch). If too much refrigerant is added, release the excess through the refrigerant gauge. Excess refrigerant can reduce cooling efficiency, increase the compressor's workload, and shorten its normal lifespan.
