What Causes the Car Air Conditioner to Hold Pressure but Fail to Complete Vacuum Extraction?
2 Answers
Car air conditioner failing to complete vacuum extraction despite holding pressure may result from the following causes: 1. Ground leakage: Air leakage at the grounding point during vacuum extraction, loose connections, or a malfunctioning vacuum pump. 2. Pipe damage: Cracks or ruptures in the air conditioner's vacuum pipes can lead to this issue. 3. Poor sealing: Gasket leaks or ruptured sealing rings that hold positive pressure but leak under negative pressure is another contributing factor. Additional information: Incomplete extraction leaves moisture and non-condensable gases inside, severely damaging the AC system. Lubricating oil reacting with moisture forms acids that corrode internal components, shortening the system's lifespan. It also disrupts normal refrigerant flow.
I encountered a similar situation just the other day. The AC pressure test showed no leaks in the pipes, but the vacuum just wouldn’t hold, which was absolutely frustrating. This is usually due to residual moisture in the system, especially in summer when humidity is high—the water vapor evaporates and gets pulled out by the vacuum pump, making it hard to achieve a complete vacuum. It could also be that the refrigeration oil has too many impurities, clogging the vacuum path, or your vacuum pump isn’t powerful enough. Don’t forget to check if the dryer is failing—it’s supposed to absorb moisture. When evacuating, open all the valves in the piping and hold the vacuum for at least half an hour to be safe. Don’t rush to add refrigerant; make sure the vacuum meets the standard first, or you’ll end up with poor cooling performance and potential compressor damage.
