No heat from vents : Duct work problems ?

Hello, I noticed that, when the central heat is on in our house, two vents (in two bedrooms) don't seem to have any air flow out of them (they are the only vents in the room, so I don't think they are intake vents) . So these rooms feel cold. Other vents in the house seem to work and hot air comes out from them. But nothing from these two vents...
I would appreciate any assistance to help me understand what I have at my hands -
1) If this seems like a duct work problem, how are such issues fixed ? Is it very expensive ? 2) Can duct work get dis-connected within the walls ? If so, does someone have to tear open the walls to fix it ?
Thanks much.
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snipped-for-privacy@gmail.com wrote:

I had one going to a kids bedroom that stopped working. The kid was dropping things like playing cards through the grate. I had to snip it open and clean it out.
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Thanks. Sorry for my ignorance here...I have no idea about how ducts are constructed . But how do I find if it is obstructed or broken ? It could be somewhere deep in the duct work. I tried peeping in and couldn't see anything.
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snipped-for-privacy@gmail.com wrote:

In my case, the duct ran straight down the wall from the 2nd floor where it was exposed in the basement. It's been so long ago that I cannot remember how I knew my son was dumping stuff in it. I probably removed the grate and peered down with a flashlight. Others have mentioned checking for closed dampers. I would imagine that any dampers would be in exposed areas.
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On Apr 1, 1:09 pm, snipped-for-privacy@gmail.com wrote:

You could have dampers near the furnace, I had the imstalled to balance my system or close off a room not used
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On Apr 1, 1:09 pm, snipped-for-privacy@gmail.com wrote:

Ducts are pretty simple and generally not much goes wrong with them. The first thing to check is whether the vent itself is turned off (closed). Sometimes they have a lever or something that lets you open and close it. If you can see through the vent grate into the 'dark beyond' then it's open. You can also compare its appearance to other vents that work. If the vents are open, there may be a baffle in the ductwork that is closed. This would probably be located someplace where the ductwork is exposed, like the basement. The main strategy there is first try to figure out which duct(s) leads to the rooms in question. By the way, are the two non-working vents on opposite sides of the same wall? In that case it may be one duct that serves both vents. Anyway if you can find the right duct(s) in the basement, look for levers or handle-like things sticking out from the ductwork. If you find one then try switching the position and see what happens. If that doesn't pan out, maybe it's time to call the heating and cooling company. Very unlikely that it would involve tearing up walls. -- H
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On Apr 1, 2:09 pm, snipped-for-privacy@gmail.com wrote:

Go down in the basement and look for damper handles on the ductwork. You should have dampers in each duct so you can control the amount of air to each vent. Perhaps you have one or two dampers that are closed. The handles should have some resistance to them as you feel the damper turning inside the duct.
A while back I spent an afternoon mapping the ductwork in my house. I simply turned the blower on high, closed all the dampers in the basement and then opened them one at a time, walking through the house, feeling the air at each vent. I then went back to the basement and used a Sharpie to mark the room location on the ductwork next to each damper handle. I found that in some cases, one damper closed off more then one vent.
It really helped me balance the output better by closing off rooms where I wanted it warmer/cooler and half-closing dampers for areas the didn't need as much heat/cool.
Remember that hot air rises and cool air falls, so the vents should be re-balanced when you switch from heat to AC.
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Thanks Everyone for your suggestions. Much appreciated. I will try looking for the dampers in the basement and hopefully I find the right one.
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they may have dampers in those runs and they may be shut.
s

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snipped-for-privacy@gmail.com wrote:

Do you have flexible ductwork in the attic? It's not unheard of for a "Y" joint to come loose there.
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