Battery draw and buzzing coming from behind glove box

[Viperlover]

I believe this has something to do with the heater fan because it started after I hooked it back up. This is in my 71 Monte Carlo.

So the battery is completely flat. When I tried charging it tonight I heard a buzzing coming from the car. I could also feel a faint vibration on the passenger side of the firewall.

After investigating a bit I found that the buzzing is coming from some box with wires coming from the bottom that is right behind the glove box. The buzzing got louder as I opened the door and activated the interior light, but it had a bit of delay to it. When I pushed the button in to turn the light off it took a second to quiet down, but still buzzes.

Has anyone ran into this before with a Chevelle or any other old GM vehicle?

I would like to get this figured out soon so I can take this freshly T56 swapped Monte out and rip some ass.