I am replacing my central A C. with a new one.

By George, you've got it.Front seat (screw in) the high side and run the unit. Do not let it pull into a vacuum as this will allow air to be sucked into the system when you open it. Also, watch you high side gage. Don't go over 400 psi. This is usually the High pressure cut out setting on most safeties. Pull low side to about 2-3 psi and kill unit. Let sit for about 5 minutes and then run it again back down to 2-3 psi. Front seat the low side any you should be good to go.
I strongly suggest that you add a filter/dryer to the system. It's good practice to do so once the system has been open. If you are going back with a 410-a system, don't leave it open to the atmosphere for more than 15 minutes. That is, the condensing unit. The only way to remove moisture from the oil on this system is to use filter/dryers. You can not vacuum it out like in the old days with R-12.

Good luck and hope this is what you are looking for.