The rear coil sometimes gets covered with bull, it is an easy fix.
Pink slime though, what is that and where did it come from would be my question.
Oh to answer the Q - having a tech mess with it would cost more than replacing.
You could unplug the AC, try rinsing out the back coil with a garden hose but let it sit and dry for a few hours before plugging back in and powering on.
BTW in this video, I do not know what he is spraying but when I rinsed mine off I never used anything. So you see where he is spraying that stuff? Just spray with a garden hose with a nozzle attached, do not use a pressure washer.
BTW you do this at your own risk. It usually works fine and helps the AC run at max efficiency
[media=https://youtu.be/QXrQHJrbbXU]