Low air flow to only some vents

[bigwillie23]

Hello,

I just purchased a single family home with dual zone air conditioning. I am having low air flow from some of my vents and I'm not sure why. This is the upstairs system.

I checked the return air units and intake, and they seem fine. Even with max air intake (removed air filter), the same low flow vents remain very low flow. What could possibly be causing this?

Any suggestion would be grateful.

Thanks

[spyder24]

Hello,

I just purchased a single family home with dual zone air conditioning. I am having low air flow from some of my vents and I'm not sure why. This is the upstairs system.

I checked the return air units and intake, and they seem fine. Even with max air intake (removed air filter), the same low flow vents remain very low flow. What could possibly be causing this?

Any suggestion would be grateful.

Thanks

Do you have in-line duct dampers installed by any chance? If so, make sure the dampers are not closed. Where the are offending registers located in relation to your air handler?

[bigwillie23]

I'm not sure about dampers, but the vents that are having low air flow were blowing well just last week. These are the furthest vents away from the center of the house (where I assume the AC unit is centered). I have closed the most centered vents in hopes to increase the flow to the outer ones, but that didn't do the trick. Very puzzling to me.

Also, there are two intake vents into the attic system. One (18x18) has a stronger flow than the other (14x14)...could this be a possible cause?

[hangfirew8]

Any suggestion would be grateful.

Disconnected flex duct in the attic?

-HF

[mbarson]

See if these folks have someone in your area to diagnose the problem... http://www.nationalcomfortinstitute.com/