Question #1: When pulling a vacuum, is it ok to have the service valves on the condenser unit open. I ask this because I would think that pulling a vacuum on the entire system (evaporator coil/line set/condenser), would actually pull the oil that is stored in the compressor out, causing some sort of mess or possibly messing up the vacuum pump. Im sure the more experienced guys will laugh at this, but am I just over-thinking all of this?
Question #2: What exactly is the step-by-step procedure when sweeping a system(line set & evaporator coil, condenser service valves closed) with nitrogen? If after pulling a vacuum, you released a nitrogen charge into the system either on the high side or the low side, wouldn't the charge just stop at the expansion valve and not be able to flow all the way through? In my mind I thought the idea was to close off one side, charge the nitrogen in on the other side, let the pressure build, and then let open the other side releasing the nitrogen charge and blowing/sweeping out all the sludge/debris?