Review on 🔧 ERGAOBOY AC R410A Valve Core Removal and Installation Tool | Dual SAE 1/4" and 5/16" Port Sizes | Air Conditioner Repair Tool for R22 R32 R134A HVAC System by Chad Judex

It takes a bit of skill to use properly. First, do not attempt to switch the high pressure side while the compressor is running. If you want to make it easier on yourself, close the valve on the high-pressure line and let the compressor reduce the pressure in the lines to almost zero. Vacuum - it will be very difficult for you if you have a vacuum. Less than 20psi is good. There is a groove at the end of the piston and there is some toughness inside that holds the valve stem in place when it is fully engaged. Practice with the new stem before trying on the AC unit. It appears to be magnetic but I think it's a silicone bar or something. When engaged, it holds the stem and lifts it easily. If it's not fully engaged, the stock will stay in place and you'll end up with an empty chamber. It's a bit like fishing - you have to carefully lift the plunger over the butterfly. I have had 100% success with this kit on R410A and R22 systems. I'm not worried about POE cross-contamination with mineral oil as there is rarely any oil left in the chamber after I'm done. Be sure to tighten all connections before use. Also, replace the high and low side at the same time as they are more likely to fail at the same time, especially if you have the system dragged.