I have the 20 inch fourth generation iMac and a few weeks ago, I noticed some condensation underneath the screen. Apparently there are actually two glass panels and the condensation was between these two panels. At first I thought I had somehow spit on the screen, but when I tried to wipe it away it remained. Later more spots appeared in a different area. I turned it off for about four days, but all of the spots remained.

I called Apple and they scheduled an appointment for me at the nearest Apple store. I brought it to the store and a guy then took it into a back room where he wiped it clean for about 10 minutes. I asked him if he thought it would happen again, and he completely dodged the question. I hope it doesn’t come back, because although it is small it’s a pain to lug it through a mall. He missed a spot two, it’s very small but also kind of annoying.

I’ll update this blog is anything else happens, but apparently if this happens to you… you’ll just have to take it to a store where they’ll wipe it clean and then you just have to hope the condensation doesn’t come back. Also, I highly recommend scheduling an appointment. When I got there, there was a big sign at the Genius Bar that said the rest of the day was booked and they could see no other customers. Also, I didn’t know what to do when I got there… just go back to the Genius Bar and wait until they call out your name. They don’t wait for you to show up for very long, so make sure you’re there on time.