How to Evacuate a Car Air Conditioning System?
2 Answers
Steps for evacuating a car air conditioning system: 1. Connect the pipes: Attach the hoses of the car refrigerant recovery and charging machine to the high and low-pressure pipes of the car air conditioning system (red connects to the high-pressure pipe, blue connects to the low-pressure pipe). 2. Power-on self-check: After turning on the refrigerant recovery and charging machine, there will be a self-check process. 3. Evacuate: Once the self-check is completed, follow the prompts on the machine's buttons and screen to perform the evacuation operation. Here is some relevant information: Before repairing the air conditioning system, it is necessary to remove air and moisture from the system. This reduces the internal moisture content, making it easier to diagnose faults and perform repairs. In fact, evacuation does not directly remove all moisture from the air conditioning system. Instead, it creates a vacuum environment inside the system, lowering the boiling point of water. This allows the moisture to convert into water vapor, which is then more easily extracted from the system.
As a technical supervisor at an auto repair shop, I often perform AC vacuuming myself. The key to this task is preparing professional tools: a vacuum pump and a manifold gauge set. First, connect the blue hose to the vacuum pump's inlet, and attach the red and blue hoses to the high and low-pressure service ports of the AC system, respectively. Open the high and low-pressure valves on the gauge, start the vacuum pump, and watch the gauge needle drop leftward below the 30-inch mercury mark. Maintain vacuuming for at least half an hour while monitoring the needle's stability. If the pressure rises, check for leaks immediately. After completion, close the gauge valves before turning off the vacuum pump to prevent air backflow. Vacuuming thoroughly removes moisture and contaminants from the system—otherwise, refrigerant mixed with air can corrode compressor pipelines, leading to complete AC failure.
