Heater Problem
 

Just yesterday the heater on my 1993 Siverado short bed, started making a hellacious banging noise. Sounds about like if someone was banging on the hood with a ball bat.

I think it is a heater damper banging open & closed, at least the noise is coming from the heater box.

It is definatly not an overheating problem. It only does this for a minute or so just after I start it up or shut it down.

Im thinking it is some sort of a vacuum, diaphram or perhaps a control problem. Near as I can tell, everything still works. I have used my air conditioner a few times this summer but it doesn't seam to matter if it is air or heat.

I bought this truck new and it has never done this before. Any advice would be appreciated.

there is an electric motor which controls the recirculation door. inside the little black box-motor is plastic gears. it sounds like you may have something blocking the door & that took out the gears. either way you need to replace the motor & manually operate door to check for obstructions. just make sure there are no children around as you are going to swear alot doing the motor job. I suggest removing the heater box assy.