I sight camera sometimes no image but always green light

Any app using the Isight camera has a black screen and the green light on.

Resetting the SMC fixes the problem, but the next day when I go use it, the screen is black again and I have to reset the SMC again to fix it.

I wiped the HD and installed a fresh copy of OS X 10.11.6. Still the problem exists.

Also when it happens I have tried the terminal commands to kill the video, and a reboot, but that doesn’t help. Only the SMC reset fixes it

Any thoughts?

Thanks