What are the operational steps for evacuating a car air conditioning system?
2 Answers
Before evacuating the car air conditioning system, the refrigerant inside the system must be recovered. The specific operational steps are as follows: 1. Connect the charging machine hoses: Connect 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 and self-check: After turning on the refrigerant recovery and charging machine, there will be a self-check process. 3. Open the high and low-pressure manual valves and start the vacuum pump: Observe the pressure gauge needle, which will show a vacuum reading. At the same time, monitor the values on the pressure gauge, with the optimal evacuation range being 98.7-99.9 kPa. 4. Close the high and low-pressure manual valves and the vacuum pump: When the system pressure approaches vacuum pressure, first close the high and low-pressure manual valves, then turn off the vacuum pump. Pay attention to the closing sequence to prevent air from re-entering the system due to incorrect order.
I've done the AC vacuum evacuation process quite a few times in my garage. First step is to prepare the vacuum pump and manifold gauge set, connecting them to the high and low pressure ports of the AC system to ensure a tight seal. Second step is to start the vacuum pump and monitor the gauge until the pressure drops below approximately -30 inches of mercury (inHg) for an effective evacuation. Typically, it takes 30 minutes to an hour to thoroughly remove air and moisture. Third step is to check for leaks - if the pressure gauge remains stable without rising, then it's good to proceed; otherwise, you'll need to locate and fix the leak before continuing. Only after completing these steps can you proceed with refrigerant charging. The whole process requires patience, as insufficient moisture removal can lead to ice blockage or compressor corrosion, affecting system longevity. A properly evacuated AC system cools faster and is more energy-efficient. I recommend DIY enthusiasts invest in a high-quality pump to avoid repeated attempts that compromise efficiency. Don't forget to wear gloves for protection and ensure proper ventilation in the workspace - never perform this in enclosed spaces. Safety first is always the right approach. If you're unsure, it's perfectly fine to leave it to professional shops.
