Is it a relay or what?

Under the back seat of my 69' bug on the left side between the heat duct and side rail the regulater is mounted I know. Between the duct and the tunnel though, is a smaller unit, that the best I can make of from the limited info in my Bentley service manual, is a relay for the rear window defogger. There are four wires connected to it, 3 black and one white. One of the black wires (a heavier gage than the rest,16-18 maybe) runs from the relay(?) to a large black plastic in-line fuse holder that is broken and disconnected, then continues as a red wire of same gauge, to the B+ terminal on the regulater. Of the other wires, one runs into a harness and towards the front. The others into a harness and rearward. It has been recommended to me by one guy, not to use the rear window defogger because it's a piece of crap, and it can cause problems. Can I just disconnect it from the regulator and leave it under the seat?

The wires into the harness to the front goes to the defogger switch, which is located under the dash to the left of the ash tray. The black into white wire is power for the defogger, and the other wires go to the window itself.

It won't do any harm to leave it the way it is. Most of the window grids are shot on these things and don't work anyway.

You will also notice an icon on the speedometer that looks like a curly pig's tail. That is the indicator light for when the de-fogger is energized. If you flip the switch and the green light comes on, then you have power to the switch and indicator light, but doesn;t necessarily mean that the window grid is energized.

If you're not going to use the de-fogger, this switch is good for other accessories you may add, like fog lights, as long as you wire it correctly.