One heating vent makes a different noise than all the others?

[CLK_2006]

I have a forced hot air system. All of my heating vents (except one) make a steady hissing sound during a warming cycle. However, one of them makes a sputtering noise. Is this anything to be concerned with? Perhaps, I need to have an escape valve replaced? They all seem to work fine warming the house. I don't want to call a repair service for no good reason.

 

[Derek]

first pull the register and see if that helps, if not it may be a ductwork issue, like maybe the air is bypassing that run sometimes. other than that with the description, i dont know.