I have a 2008 F-150 FX4 5.4 Flex fuel. I recently had a new/used motor put in along with brand new a/c system. A week after getting it back, all my gauges, radio, windows and cold a/c stopped working. It will blow hot. Anyways, took it to a mechanic, was told the instrument cluster was bad. Plugged in new one, nothing different. Was told by another mechanic it was the ignition lock cylinder because I had had issues starting randomly. Looked on a few forums and decided to check fuse 21. Low and behold, it was blown. So I went to replace it, and 10 fuses later, they keep blowing. At the point I’m at now, I have found with a new fuse and only the right connected plugged in, the radio, windows and a few light and one gauge work. With the other connector plugged in, it blows the fuse. So my problem is in the left cluster connector/ wires. On my way home with just the right plugged in, I stop and take my key out and boom. Fuse blew. I’m not sure which wire is the bad one. Anyone have any ideas?

 

This is just an idea.
If you have the owner's manual, check in the fuse and relay section and see just what that particular fuse protects. It will list there what circuits the fuse covers. That will get you in the ball park. Start looking for pinched wires ,that might have been done by previous repairs.
Of course if someone can provide a wiring diagram, that is the better way to go, because you know where the wires go and can spend less time looking and checking.
This requires someone with a little electrical savvy and should be pretty easy to pin down.

 

Here are some diagrams with parts highlighted that are relevant.w
As you noted there are two connectors for the instrument cluster. Based on the attached pictures can you specify which you are calling the right one and the left one, C220A & C220B are the connector names. Some people talk about left and right sitting in the drivers seat, others talk about it standing in front the truck looking at it. Its a little thing but it can be very confusing when both people are talking about different sides.
Also might I suggest checking the other fuses shown to power up the instrument cluster, while they are unlikely to be blown since they power up other components as well it would be good to know they have not blown.
Also was the evac case removed during the installation of your brand new AC system?

 

I have this ame problem on my 2006 f150 king ranch has there been a fix for it yet