That's not what we're saying. You said that the system is already "empty", meaning the chemicals have already leaked out and the system is vented to the atmosphere. However, its not actually "empty". There is air and amospheric moisture still in there now and there still will be after you change the lines. The system has to be brought to a vacuum state with nothing in it prior to charging. All that natural air and moisture has to be removed first, if that makes it more clear. If you have no way to evacuate the system, you can finish the line installation, but you can't completely finish the job.fine. will get lines evacuated properly by a professional so as not to burn another small hole in the ozone layer.
Like PP is trying to tell you, the system needs to be evacuated before charging. That means a vacuum pump must be hooked to the system to draw out any "non-condensable" or inert vaports (and, most inportantly moisture) and then if done properly micron readings taken to be sure an acceptable level of vacuum is achieved (this is a good indicator how much moisture has been drawn out).
That is why there are trained profesionals for this type of stuff, so don't get all upset, we are just trying to help.
those lock on when you push them together. If you are taking the old ones apart, you need a set of plastic fitting removal tools. The set is like 15 bucks. They fit over the line and push up inside to spread open a snap ring type fitting so the lines will pull apart.