Thanks for all the replies. I'm really bad at soldering so to me that's not really an option. I thought possibly the firmware might be dated but it turns out I have the latest one.

I'll try replacing the fan. If that doesn't work I don't know what I'll do. Maybe turn it off at night.
I tried using one of my PC case's fans but it didn't fit. It's weird. The fan from my PC case has a 4 pin connector but it's a different 4 pin connector. Maybe because the one from the Antminer is a higher powered fan? I'll try to go at my local computer store and see if they have that model of fans.