Hold On

Working on a 83S. Since the entire dash and console is out of the car,Im using this time to sort out a problem with my HVAC. Everything within the HVAC head unit appears to work correctly. The vents change as slider positions are moved and the a/c works great. Heat works great also. The only issue I seem to have is when I move the selector slider full left to the OFF position. I get a load buzz noise until I move the selector to another position. It sounds like its coming dirrectly from the head unit area.

I have spent a lot of time reading various threads and the popular help sites.

Some people have mentioned its the internal relay inside the head unit. Unless I misunderstood, that relay controls the a/c clutch operation. Correct me if I`m wrong. This noise occurs independent of a/c on or off.

Could one of the vacuum actuators under console be making that buzzing? What other issue could cause that load buzzing noise only in the OFF position??

Thanks,Kevin