High and Low side a/c
Low side is liquid. High side is gas/vapor
NO IT IS NOT. the low side returning to the compressor is mostly cool but wet vapor, and must have some droplets to cool the compressor head and valves. On many systems this is checked/ established by superheat, which is the difference between the measured temperature of the tube (insulated) and the saturation temperature equivalent as read off the gauge/ chart at the pressure measured.
High side OUT OF THE COMPRESSOR is high pressure very high temp hot gas. After it leaves the condenser, it is cool, high pressure, liquid.
In a normal healthy system with good compressor valves, you will NEVER hurt a system by liquid charging the high side. The valves are what keeps liquid out of the compressor during shutdown, as it can migrate back from the condenser towards the compressor.
In my days servicing refrigeration/ HVAC stationary systems I have NEVER hurt a system by liquid charging into the high side.
You can liquid charge into the low side ONLY while in operation, and you must monitor operating pressures, use your head and ears, and meter the liquid so it does not "slug" the compressor. I have also done THAT lots of times, and NEVER slugged a compressor
YOU CAN NOT charge liquid or gas into the high side while in operation, unless it's pretty much empty and should not be running in that case. (Low pressure switch)
You can charge either liquid or gas into the low side while in operation. DO NOT charge liquid into the low side with the system off. If it gets to the compressor, it will sit there and when put into operation, it will hydraulic lock
