What are the reasons for car air conditioning not leaking under pressure and incomplete vacuum extraction?
2 Answers
Car air conditioning not leaking under pressure and incomplete vacuum extraction can be caused by the following reasons and solutions: 1. Poor sealing: Leaks may occur due to damaged seals where positive pressure does not leak but negative pressure does. In this case, check if the seals are intact. 2. Damage: There may be damaged areas in the pipeline. If damage is found, the pipeline should be replaced promptly. 3. Air leakage: This could be due to loose connections during vacuum extraction or a faulty vacuum pump. Tighten the connections to prevent air leakage. 4. Not using the repeated vacuum extraction method: If the repeated vacuum extraction method is not used during the process, moisture cannot be directly extracted from the refrigeration system. Instead, creating a vacuum lowers the boiling point of water, turning it into vapor which is then extracted. Using the repeated vacuum extraction method ensures maximum removal of air and moisture from the system.
Having worked in an auto repair shop for many years, I've encountered this situation quite often. A pressure test showing no issues indicates there's no obvious gas leakage, but incomplete vacuum evacuation could be due to an old or underpowered vacuum pump with insufficient suction force, leaving residual air trapped. Additionally, tiny leaks at hose connections might not be noticeable during high-pressure testing but can allow environmental air to seep in under vacuum conditions. Moisture is another concern—humidity in the AC system may not fully evaporate under low pressure, hindering the vacuum process. Remember to check if the pump oil is contaminated; replacing it with fresh oil can improve efficiency. Extending the evacuation time to over 30 minutes might solve the problem. If issues persist, consider upgrading equipment or consulting a professional to recheck pipeline connection points.
