Jim is right, but I'll take it further, ABSOLUTELY. You charge the low side on ANY system. This is a SAFETY issue. If you try to charge at the high side, you could explode the can in your hand.
Also a converted system can be tricky. Don't try to do it with a suicide hose. Use a set of manifold gauges so you can monitor the high side pressure. With most conversions this is what you have to go by unless you are charging an evacuated system by volume.