Asked on Jul 16, 2013

Air is blowing OUT the air intake vent.

by Eulenspiegel
Some workers were here today, putting in new doors and insulation in the attic.
They turned off the air with my programmable thermostat (that I don't have programmed -- I have no need for that feature) because they had the doorways opened up for quite a while.
When they left, it was 89 degrees inside.
I turned the air back on, but noticed after a while that while it brought the temperature down to 80, it didn't bring it down to what it's set at, which was 74.
I figured and am hoping that it's just a question of knowing which buttons to push.
But it's not cycling on and off.
It keeps blowing and while cold air is blowing out the registers, cool air is also blowing out the intake vent grill (right in front of the furnace filter!!)
THAT'S not right, is it!!!? 'Intake'!! Shouldn't it be sucking air IN?!!?
Does anyone know what's probably causing this?
(Naturally, it's happening in the middle of a heat wave, LOL!!!)
Thanks in advance!!!!
  10 answers
  • Your asking a few different things here. When a house becomes hot and humid it often takes several hours to drop the temp. The first thing that needs to be done is to remove a lot of the moisture. Once that happens you will find that the house temp will begin to fall. As long as the thermostat is calling for cooling the system will not cycle on and off. That will only happen once the house cools down to the setting on the thermostat that is set to. Your also saying your return grill is blowing air out of it? Put a piece of newspaper strip about two inches wide by about 12 plus inches long in front of the grill. Does the paper draw itself to the grill or blow away? If it blows away, they did something in the attic that changed the configuration of the duct connections when working on the attic project. If the air is being drawn into the filter then it is just air currents that are tricking you into thinking that the air is being blown out. IN any case if indeed air is blowing out the filter grill and not in, then something was disconnected when they were working and for the life of me someone they reconnected the return to the supply grill. If you can take a few photos showing the grill and where your feeling the air blowing out. It will help a lot in determining what is going on with the system.
  • I agree with taking a piece of paper to actually see if it is drawn into the filter grill. If it is then they somehow did something to the duct work. It also sounds like your program on your thermostat isn't set correctly. Take and make sure your thermostat is set for cooling and that your fan is set to automatic.
  • Eulenspiegel Eulenspiegel on Jul 17, 2013
    Thank you!!!! And the air IS going into the intake vent!! As to thinking that it was blowing out, I can only point to myself and paraphrase George Costanza on Seinfeld -- "For I am Eulenspiegel!!! Lord of the idiots!!!" The only thing I can say in my defense is that the reason the guys were here putting up new doors and insulation was expressly for 'weatherization'. The head guy said that I should see a big difference in my bills. Apparently, I misjudged what was happening with the intake vent because the 'flow' was so STRONG!!! I'm used to it feeling 'barely there' when the air is on!! I'm still surprised that the temperature took so long to drop only because the furnace and air are in the center of the one floor house that's less than 750 sq. ft. (We're talking small here, folks!!!! LOL!!) The fan still stayed on all night, but I turned the air off (as I always do) when leaving the house today and then back on when I came home. It is now working properly. (And I hope it continues to do so!!!) Thank you both so much for your help!!!
  • Eric Eric on Sep 02, 2013
    My tents put one of those "Nest" thermostats (programmable via internet an phone app) on my air conditioning unit. It seems cold air is now blowing out of the intake vent and hot air is blowing out of the vents. Here is a picture of stuff blowing out of intake vent. The house is not cooling down.
  • Are you sure that is the result of blowing out? That is normally a sign that dust bunnies from the floor have been sucked into the face of the grill. The air does not simply change direction because of a thermostat change. Only way that happens is if the ducts were reversed, awful hard to do even if they wanted to do that. Or the fan decided to turn itself around. Even if it started blowing backwards, air will still come out as it should, only really poorly. I have seen many grills installed wrong with the supply grills on the return or intake, and return grills on the supply side. But from what I see in the photo, that is just a collection of dust that has built up and did not make it past the grill face. And that grill is a return style. If the house is not cooling down, this can be caused by a few factors. Low on gas, outdoor unit not running, or the thermostat is wired wrong. It also can be caused by dust. Based upon what I see on the front of the grill, is the filter plugged? What about the coil above the furnace or attached to the blower system? If either one is plugged the ac will work very poorly or not at all. However as a NEST installer I can tell you those stats are the easiest to install and program. And if anything was wired wrong, it will tell you that something is not right and how to fix it.
  • John Church John Church on Apr 29, 2017

    My package unit is blowing air though the intake (which is connected correct and 5' feet away and though all the vents). It makes a lot of dust and no sense . Does anybody have a clue why this is happening?

  • Kathy Treutel Kathy Treutel on Jul 20, 2017

    Our Lennox system is doing the same thing now for several months. We have 4 zones but normally leave one zone off. 2 of the returns blows cold air out of the return vents but not out of the supply registers. I noticed today that only 1 of the thermostats showed cool ON at the time this is occurring. We have had a new hvac company out 4 times but they haven't fixed it. We have replaced all of the filters and they adjusted a "backdraft". Any ideas?

    • Glen M Isaacson Glen M Isaacson on Jul 15, 2018

      Itvdoesnt actually so7nd possible. So if you place a tissue on a return vent it will not sucknon to it, but actually blow away? And you have showed this tobrepair people who say ,yes air os blowing outbof your return but also just leave it this way. Please forward me a video of this using tisue.

      Thank you . Glen from duct boss

  • Thomas Croft Thomas Croft on Mar 09, 2019

    , I'm running my furnace in my trailer I put new filters in the furnace but my cold air return is blowing out cold air what can be the problem

  • Pam Evans Pam Evans on Mar 31, 2020

    I live in an old apartment building and the vents are at the ceiling and I have black stuff coming out and the intake vent is in the kitchen and sometime it blows air out. is this normal