Which drain pan? The secondary? No, that would mean you have an issue.
No....inside the coil assembly whatever you call it........when I look inside the little drain holes, I can see that the bottom of that unit has a thin layer of water like a little lake....it's where the water drips from the coils above and it is supposed to drain out.
Ok. I believe there should be a slight slope that will assist the water to flow out. Could be you have none. You could have some build up of rust or something slowing the flow. I don't think 100% will drain out.
digitalplumber is just a name for use here, I am not a plumber!