Teddygrammin

So I've had this issue for a while now and I can't figure it out. The brightness for the main gauge cluster isn't working. They do light up but during the day but when it's suppose to be the brightest, they're dim. I thought it was an LED inside the cluster and i couldn't find anything. I sourced a Nismo cluster, swapped it out and I'm still having the same issue so I can rule out the cluster. At night when the headlights are on and the cluster is dimmer, I can use the brightness controls but never all the way bright.

I've done some research and the only thing I was finding was the AC amp climate control box under the radio. I don't want to just start swapping parts. Has anyone ever had this issue and maybe point me in the right direction?