+ Reply to Thread
Results 1 to 9 of 9

Hybrid View

  1. #1
    Join Date
    Jun 2011
    Posts
    4

    Default air flow problems

    I am having an air flow problem after my central a/c runs for 2 or 3 days, I notice that the air flow coming out of the vents starts to decrease. I have changed the filters, the evaporator is clean and dont appears to be icing over, its a one speed blower motor, the only I see is that the ducts have a lot of condensation dripping of the ducts. Any Ideas?
    Thanks

  2. #2
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    5,103

    Default Re: air flow problems

    You seem to have more than one problem here.

    How old is your cooling system? What kind of ducts do you have? galv sheet metal, I bet. Are they dirty inside? Get up into the attic early in the morning and check your ducting system, connections, tape around them, hangers - a complete check up. See if any air is escaping out from the ducts.

    The drip is probably caused by higher than normal temperatures and humidity levels this year. Start running your a/c early, before it gets very hot or too humid and set your desired temp at 79-80, not the low to mid 70's.

    If you have metal ducts, consider replacing them with new insulated flex ducts.

    Also, have an a/c tech perform a complete tune up, to include checking the coil compartment. Clean the pyramid, if necessary.

    The sooner you tend to your problems, the better.

  3. #3
    Join Date
    Dec 2007
    Location
    Tennessee
    Posts
    1,381

    Default Re: air flow problems

    Condensation in the ducts means you have a major problem, but one that is probably easily fixed and not very expensive either.

    First thing to check is the drain underneath the evaporator coils. If the tray under the evaporator coils is filling up with water, then you need to have the drain line blown out.

    The other source of condensation would be from warm moist air entering your ducts after the evaporator. Now I know the ducts have positive air pressure so any leaks should be from the inside of the duct out, not drawing air in, but you might have a leak that is acting like a venturi. The principle here is MMF or motomotive force. If the breach in the duct points backward from the direction of the airflow, then the airflow will create a vacuum in the breach and draw air in. To fix this would be to find the breach and seal it, or just seal all the joints in the ductwork.

    BTW, I think you do have a little icing of the coils, just not that bad yet.

  4. #4
    Join Date
    Jul 2009
    Location
    Northeast
    Posts
    661

    Default Re: air flow problems

    Sounds like your ductwork needs to be insulated, as for changing to flexduct I wouldn't as you'll lose more air, unless you go to the next size up. Nothing is better that metal for ductwork, flex is just quicker to install and cheaper.

  5. #5
    Join Date
    Jun 2011
    Posts
    4

    Default Re: air flow problems

    UPDATE
    The ducts have been sealed, the drain pipe has been blown out, the system is 8 years old and in the basement that is a walkout basement, and it has metal ducts that I cleaned last summer because of the same problem. Had two A/C companies in to look at it last summer and neither one found anything wrong.

  6. #6
    Join Date
    Feb 2012
    Location
    Minnesota
    Posts
    3

    Default Re: air flow problems

    Rather than create a new thread, I thought I might piggy back on this one, as I'm having one issue that's similar.

    I'm not having the condensation issues whatsoever, thankfully, but am having some issues with uneven cooling/heating on the second floor.

    Not too long ago, I had someone come out to repair the outdoor AC unit as it was no longer producing cold air. Fortunately it was a quick replacement of the capacitor in the unit.

    During the service call, the HVAC repairman found some partially closed dampers and went through and opened them. This certainly increased the air flow through the registers, but I'm still having issues cooling the second floor.

    I'm considering trying to close off (not completely) the duct work to the first floor, but am not entirely sure which ducts go where. I'm fairly confident of which one feeds the second floor, as one of the paths goes up the middle of the house rather.

    The remaining duct work goes to the outer wall of the house in two cases and into the middle in one case - all of which go directly up to where a vent is on the first floor.

    My plan is to close the dampers to those ducts to see if it helps the output on the second floor, then partially re-open each of the others. Does this make sense as an attempt to rebalance, or am I taking a big risk with this plan?

    Thanks!

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •