One bedroom in our house gets no air hot or cold coming out of the ceiling vent. Our house has a flat foam roof. Can someone tell me what to look for to fix this problem. All other vents in the house work fine.
Either a damper is wrongly in the closed position or ducting has come loose. If it is an adjustable damper, then it should in an accessible location, e.g., in an attic utility space. Another possibility is that a duct is plugged or crushed.
If you want to try to analyze the problem yourself, remove the register grill in the room and see what you can. If the duct makes a turn near the register, then you won't be able to see far. You could lay a flashlight inside, then use a mirror on a rod to look inside the ductwork.
I would think that there are cameras that are used to look inside HVAC ductwork, but that would be a professional instrument. Plumbers use those to examine sewage drain lines and you'd want to be sure if you got the use of a camera that it had never been used on drains.