I wanted to make it known, since I've learned this $30 lesson for myself, that you DO NOT remove the original low side port's valve core when you install a new port for 134a. My retrofit kit said nary a word on whether I leave it or remove it, so I decided that since the new port has a valve core in it, mine would just be in the way. Not true. So for now I have the charge hose still on the port, neatly tucked out of the way of course, but have cold A/C. Thought I'd share in case someone does a search in the future about this topic.