Asked on Jun 9, 2012

A/C question: My outside unit runs, but no air is being pushed through the vents in the house.

Car48061903Colleen SmithRyan


It has been about a year since my last tune up, and I am wondering if a tuneup might be all I need, in order to avoid a service call and diagnostic fee and any other charges that may come along with all that. Thanks as always for your input!
46 answers
  • Walter Reeves
    on Jun 10, 2012

    Sounds like something amiss in the air handler (fan unit). Is it in a place where you can get close and listen to it?

  • KMS Woodworks
    on Jun 10, 2012

    there may also be some clogging of the coil...time to look a bit closer at the fan / coil area.

  • The inside fan is not running it can be one or two things. Fan that blows in house has a burnt out motor, or the relay that controls both the outdoor unit and the interior fan system is not turning the inside unit. Normal operation is to turn on inside fan and a few seconds the inside turns on. Check to see if the filter has not been sucked into the fan inside causing it to freeze.

  • Alan W
    on Jul 11, 2012

    Go to the indoor unit, that is where your problem is. Remove the panels and then manually press the interlocking switch and see if the motor turn. If so the problem is that the squarely gage assembly has come loose from the motor. If the motor does not turn on, then you most liked need a new blower motor. To check it remove the leads from the control board to the motor, and apply 110volt leads to the black and one other color wire. If the motor runs you need a new control board, if not you need a new blower motor.

  • Sandra M
    on Jul 13, 2012

    My outside unit sometimes does not run when even though air is coming through the vents. When I flip the breaker switches off and on a time or 2 the outside unit will then come on. (The breakers are not flipped off, I just turn them off and on myself.) I just replaced the condenser (or compressor??) last summer. I can't tell if I have another a/c problem or whether it is an electrical problem. Can more power be added to the electric box? Sorry the terms not being right...

  • Sandra M
    on Jul 13, 2012

    My problem is the opposite! Don't know if I should call a/c guy or electrician.

    • Fonda Hester Goodman
      on Jan 4, 2018

      I am having this issue, it even happens in emergeceny heat. My unit stops kicking on in the inside, the auxilary light even comes on but the fan will not come one. I have gotten it to start by fliping the inside unit breaker off and then on in the past. I dont know what to do, my heat and air guy has been out 3 times, once the capasitor was changed, yesterday the coils cleaned and the other day nothing was found. please help!
  • Ok, if the inside is working and the outside is not there are a few things you can check on your own. The electrical power that feeds the outside unit has either a fuse or disconnect switch. If the fuse blew then you simply need another one. To check that you need to open up the little door where the wires exit on the wall of the house. There should be a little handle there. Pull that out to see if there are fuses on the other side of it. No fuses, simply put it back in the same way it came out. If you look at the handle it may have a off and on logo imprinted on the face. Be sure you can read On and place it in that way. If there are no fuses on the outside, you need to check your breaker panel or fuse panel in the house that feeds the unit. See if the breaker has tripped or the fuse has blown. Reset if it did happen and you should be fine. Change the fuse if it blew. What causes the fuse or breakers to blow is short cycles. If your in an area which the power has gone off and on quickly a lot that will in many cases cause the breaker to trip or fuse to blow. If you ruled out the breaker or fuse, then you need to see if the system is calling for cooling on the outside. Have someone inside the house turn the thermostat up and down. Listen for a click sound on the outside unit. If you have a set back type of thermostat you may need to wait about one min for the sound to happen. If it clicks and the outside unit does not hum or make any noise, then either the unit is low on refrigerant or the run capacitor is burnt out, Both are common issues. in any case a AC person is all that is needed if you ruled out the breaker or fuse.

  • Alan W
    on Jul 14, 2012

    if the outside unit is not working. It can be several things. first it can be the 24 volt relay that trips the 230 volt line. To test this, turn the inside thermostat all the way down and go to the outside unit and turn the power off to the unit (breaker box). Open the unit and see if the relay is engaging the 230 volt leads. If you are uncertain then take a wooden object and push down on the ceramic bar that connects the contactors. If it has play, you are not activating the 24 volt relay. To verify this, turn the 230 volts on, and again using a wooden (non conductive object) press on the ceramic bar and see if the unit starts. If so get a new contactor assembly. If it is o.k. then you either have a bad capacitor (the fan should turn slowly ) or a bad fan motor, If when you turn on the unit and it quickly trips the circuit breaker, you most likely have a bad compressor. In either case you should get professional help.

  • Sandra M
    on Jul 15, 2012

    Thank you so much for your help! Sounds like I need to call an A/C pro. August is almost here!

  • Joan Good
    on Jul 21, 2012

    If the outside unit is running but no air is blowing inside, check that the returns aren't blocked, check that the filter is clean, and if that's not it, it's probably the fan or the blower motor (in my case, about a $500 repair) or the control board. If everything inside is working, warm air is blowing, but the unit outside isn't turning on, it may be as simple as a tripped breaker to the AC unit, or as expensive as a dead AC unit. An AC pro is the way to go with that! Sadly, we've had to deal with that as well and it was more expensive, but we were able to get a unit that was a better fit to the size of the house and more energy efficient than the old one that the builder had installed. If you have to replace, ask about rebates from the govt and the power company for installing new equipment!

  • Christel J
    on Aug 23, 2012

    that just happened to me and it was the thermostat inside that needed replacing

    • J
      on Jul 28, 2018

      That was just said to you so they can sell you a $35 thermostat for $200 i know they did it to me once.. and tried again, but i told them if i am going to pay $200 for a new one i want one that costs $200 not $35... he said well we can out anyone on you want as long as you buy it and pay us $200 to install it.. i lol's and said man if i buy it i am going to install it not pay you to do something a 5 year old can do..

  • Kc
    on May 21, 2014

    My outside fan is running but theres barely any air coming through the vents...I even places a thermostat on the vent and its registering the temp I have it set on (70*) and its 78* in my house

  • @Kc this can be an issue with the charge in the system. To see if that is the case, go outside and check the pipes that enter into the outdoor condensing unit. If they are iced up you need to turn off the AC system and turn on the fan switch to on position not auto. This will continue to run the blower and assist in melting the ice on the indoor coil that has frozen over thus slowing the air flow to almost nothing if anything at all at the grill openings. Running the fan will also help prevent the ice as it melts from dripping outside of the collection pan inside that would cause water on the floor. Will not prevent this completely, but will help a bit. Check your air filter also. If its plugged and your system is just a bit low on Freon, that may be enough to cause it to freeze over. AC systems need 400 cubic feet of air per ton of air conditioning capacity to properly work. Less air means colder coils that means frozen pipes. If you find the filter is clean, you will need the assistance of a professional to recharge your system.

  • Mike Robbins
    on Jun 28, 2014

    I have just purchased a mobile home. The ac unit outside comes on, but I get no air through the vents. Also, there is no air being pulled from the return vent. Im a do-it-yourself kind of person and would like to know what may be causing this problem? You can email me directly at Thanks again!

    • @Mike Robbins one other thing to try to see if it is the motor on the air handler or the controls is to switch the thermostat to heating, set the temperature up so the unit runs. Many systems will have multiple (typically two speed) fans, high speed for cooling and a lower speed for heating. If the fan comes on in low speed it is probably a control issue, maybe the main control board or even a broke or lose wire. The other possibility is what WE mentioned above, the A coil is so frozen up that no air can get through to the duct work. Did you notice a slow decline in air flow or just all of a sudden drop in air? If gradual, that may be problem as well, low refrigerant or setting your thermostat way too low causing the system to freeze up.

  • Mike the first thing to try is to switch the thermostat from Auto to On for the fan unit. If the fan does come on and blows air it pretty much tells you that your motor is good and that the problem is with the control circuitry (probably a solid state relay on an older system). Typically most residential units are a single fan system, only commercial units have separate supply and return fans so the fact that you have no return is not of concern, the air handler is not coming on or working. Depending on the system it is also possible that the air handler relay may be low voltage while the relay for the condensing unit (outside) is line voltage so it may be a bad step down transformer that takes the 240 VAC and produces either 24 VAC or even a DC power supply that rectifies and steps down the voltage to 24 VDC. You should be able to trouble shoot these problems with a basic volt meter.

  • PC
    on Aug 2, 2014

    Brian - I have a similar problem if you wouldn't mind helping. The outside unit is turning on and the fan inside starts to push the air through the vents. After about 2 minutes the fan stops and then no air comes out of the vents. The outside unit still continues to run but the blower motor stops.

  • If the fan stops running on the inside. either the blower motor is overheating, Turn off the power on the unit open up the panel that accesses the fan and try to manually rotate the blower wheel. If its stiff the bearings can be worn causing to much friction to the motor. There are devices in some motors that will turn off it is senses overheating. Also the capacitor can be bad on the motor. These $10 parts failing are common. If the blower turns freely, then change the capacitor. You may need a pro for this as these parts are often sold only at establishments that sell to commercial companies only

    • Curtis Haigler
      on Sep 8, 2018

      Or you can get youre units info and search Amazon if it is a capacitor, found mine on there for $20, saved a bunch of $$$👍and it was a fairly simple job to do. Just be careful though, electricity bites

  • Mike
    on Aug 4, 2014

    i have a similar problem and wanted to make sure i'm on the right track. outside unit is running fine. no air is coming out the vents. i checked the both filters in the wall and in the air handler. checked the breakers. checked and cleaned the float switch. checked the motor to see if it spins fine and it does. i pulled out the variable speed module and don't see any visible damages. should i change the module? please help.

    • Gregg Gerstenberger
      on Aug 28, 2014

      @Mike what ended up being your solution? mine is the same situation. I just had the blower/motor replaced and it started working fine, but now no air comes out of the vents at all and the air handler and outside unit continuously runs.

  • If the fan is not working inside the relay that powers it may be faulty. If the blower is running but your not getting any air, A low AC charge can cause freezing of the coil and blockage of the air flow. Sometimes you just need to power the system down let it sit and then power back up. But in most cases it sounds as though your electronic controls are faulty. Does the board have a light on it? Many do. If it does on the inside of the panel you will see a list of blinking light issues. If there is a window on the air handler, look into it with the system running. count the flashes for a pattern. Then remove the door after turning off the power and compare the flashes with the list. This will tell you what is going on. Does the fan run when switched to fan on mode on the thermostat? If not, the relay is most likely the cause. Very rare for the thermostat being at fault.

  • Mike
    on Aug 4, 2014

    no visible lights. tried shutting it down and powering it back up. air handler fan looks like it wants to start but spins a bit then stops. fan mode on thermostat is no help. same rumble, fan spins a bit then stops.

  • Relay is dropping out. Also could be faulty transformer. If the VA (volt amps) is not high enough the power is not enough to hold the relay in. But I think you need a new board. What brand is it. Can you provide the model number? Can look up some stuff on this perhaps and shed more light on the subject. Also age is important. If you know. There is a date code normally on the outdoor unit if they match.

  • Mike
    on Aug 4, 2014

    trane model#TWE037E13FB1. borrowed a friends device to manually operate the fan and it's not running. same scenario, fan starts for a bit then stops. so that eliminates the control board? pulling the fan out to see if there are any visible signs of damage. i found the light, fan light is solid green and cfm light is constant blinking. not sure how to read the blinking light

  • Nick Petrino
    on Mar 13, 2015

    im having same issue. the inside unit shuts down but outside fan keeps spinning

  • Wes
    on Apr 9, 2015

    ANSWER......I'm having the exact same problems. My ac unit is running non stop but no air. The intake wasn't pulling either. I have an hvac guy here and he first thought it was the fan relay but tested the circuit board and it is messed up. Of course the new curcuit board is $450. Hope this helps.

  • Sandy
    on May 29, 2015

    Hi Friends, I am facing an issue with our AC unit, during the night when we start the AC it works fine, but later after few hours there is no air coming in the vents but the AC unit is still on and also the blower/fan is running, I can hear the sound, hwat troubleshooting steps i can do to isolate the issue? Thank you for your time, -Sandy

  • Betty Gramse
    on Jun 25, 2015

    Mine was doing something similar. The fan was running but not cooling. My son came by and noticed it was almost 80 in the house and went to the breaker box and flipped on the switch for the AC.

  • Tonia Michelle Powers
    on Aug 1, 2015

    My fans turn but no air is coming through intake the coils are getting cold the heat doesn't work in winter

  • Betty baldwin
    on May 30, 2017

    I had a new furnace installed last fall. Then we noticed the fan on the outdoor a/c unit was running. We shut the outdoor breaker off for the winter. We just tried turning on the A/C and it works but when we switched it off at the thermostate the fan out side started running on its own again. Do you know what could cause this Thanks Betty
  • Dan23809782
    on May 30, 2017

    Have you cleaned or changed or air filter.
  • User
    on May 31, 2017

    When i turn my ac on i can hear it come on but no air come out whats the problem?
    A lil bit air comes out
    • Vernon
      on Jul 18, 2018

      I have the same issue. outside unit on. blowers on inside are on but no air through vents. 95 degrees in my home. Please help. I have a 2 yr old and she is miserable in this Texas heat.

  • User
    on May 31, 2017

    Only a lil bit air is coming thru the vent i dont why its doing that
  • Tima
    on Jun 2, 2017

    My ac compressor outside is pushing out our air and it's not coming into the apartment ?
  • Rob25103951
    on Jun 12, 2017

    I have an odd issue. My compressor is running and I can hear / feel air being pulled into the return, but no air is coming out of the supply vents. Any suggestions?
  • Annie
    on Jun 14, 2017

    I don't have a inside unit
  • Michael Bavaro
    on Jun 16, 2017

    Check out my friends website at it'll tell you all about what you should do
  • Felicia Bracamontes
    on Jul 14, 2017

    My unit is working just a dirt a little cool air was coming through then all of sudden no air at all is coming thro we just changed filters and it was working fine but then this happened

  • Karen Brock
    on Jul 14, 2017

    Sorry, your fan motor might be in need of replacement. In central Florida it's about $350 I think.
  • Gee28884595
    on Aug 7, 2017

    Ok, I have read and read and have not come upon my problem (and common sense says it ain't so). The entire unit is working fine.....except no air comes out of the vent. The filter is new, I have no duct dampeners and condensate tray is fine. It's like it's being blocked somehow but before I start tearing the duct system apart, any ideas? It was fine 2 hours ago. The unit I have, the heater portion sits on top of the cooling. I say the blower is working fine because there is air moving in the open compartment. I can not see the actual blade or motor spinning as this is a very small area to work in. HELP!!!
    • Gee28884595
      on Aug 8, 2017

      Ok, I put a camera in the unit and the blower is working fine and since the air is forced through the coil and out, I must have a problem with the coil. Now since that's a sealed unit, I can only suspect that the unit is frozen pretty solid and not allowing air to get through. I am going to let the unit sit for about 2 hours and see if it defrost. (Sometimes, just talking this through by myself, I can figure things out.)
  • Stevie Jones
    on Aug 12, 2017

    When i turn on my ac no air comes through but the outside unit is runningi dont know what the problem is. Please help me
  • Tiffany kline
    on Sep 3, 2017

    How would i know if my air froze up

  • Jennifer Baker
    on Jul 8, 2018

    Our a.c. turns on just fine but when air starts to blow inside it's Super a loud fan/air blowing. Filter is ok.... help!!!

  • Lakesha
    on Jul 14, 2018

    Do u have to have air filter so your air can work
  • Toi
    on Oct 3, 2018

    My outside unit runs, the air handler is in attic (zone 2), zone 1 is fine. The fan does run, the termostat is fine. Can the overflow switch cause the air handler to NOT blow air, but the fan still works?

    • Toi
      on Oct 3, 2018

      I'm trying to see if the overflow is activated due to water build up, would the fan be affected too. I feel slight air and hear the fan running, but when I switch to cool/heat, no air flows.

  • Ryan
    on Jul 25, 2019

    This thread has been going a long time but continues to receive regular updates and inquiries so it must be a fairly common issue.

    Here's what I am experiencing: I live in central CA, summer temps routinely get to 105 and sometimes even 110, but very little humidity. The unit is a 30 year old roof mount central heat and air system, original to the house (not sure of brand). The house is about 1,600 sqft, approximately 1/2 of which has 12' vaulted ceilings.

    The unit will act like it's going to turn on, but the fan never kicks on and no air comes from the vents. I checked the return vent, okay, filter a little dusty but not too bad. I replace filter, vacuum off register vent grate and try again.

    Same response. Turned unit off for several hours (from about 4:30 PM to 10:00 PM) thinking maybe iced up coils. It was 103 and the unit sits in the sun all day long. Left the unit off overnight (10:00 PM to 4:30 AM), it didn't get below 75 overnight (I'm mentioning temps and times because I believe I allowed adequate time for the coils to de-ice before trying again), and the problem still persists today.

    One thing that I did notice is that I do get some weak airflow coming OUT of the return vent, very cold air. If I left it on long enough, it would lower the thermostat temperature a few degrees since the thermostat is located almost directly under the return vent.

    An AC company came out and performed extensive maintenance last year. Apparently there was extensive air leaks around the unit and a few parts needed replaced. They also performed a routing cleaning and whatnot.

    What're your thoughts? Time to replace the unit?

    I have noticed the past couple months when the unit runs, water drips from it, runs down the roof and into the rain gutters. It eventually reaches the downspout with sufficient enough volume to create a small puddle at the bottom of the down spout, if that matters or helps at all.

    • Alisa Poole Lopez
      on Sep 1, 2019

      Lemme know if you get a response, please. Damn near same issues here. Gonna be a long hot miserable labor day weekend in Corcoran. 😩

  • Colleen Smith
    on Aug 11, 2019

    My home AC unit stopped blowing cause it froze up. We defrosted it,but it froze up again. My friend said it wasn't defrosted long enough so we did it for about 8hrs and then we put the panel on and it wouldn't blow cold air. It will however blow air, not really cold air but some only with the panel off.....side note we did have to clean the coils which we did but still didn't really help. Any answers

  • Car48061903
    on Sep 16, 2019

    I came to this site with no air coming from vents. Fan is running. I opened the door to my inside unit and felt air coming through the door. That is not right! I located a hole in duct work. Going to see if I can repair in the morning.

    • DebWor
      on Dec 9, 2019

      My until does this is the tray inside fills with water. Check out side. See if water is dripping out of the pipe coming from the house? If not take a water vacuum and hold it there. It should start to pull out alot of water. You can also go to where your indoor unit is vacuum out the tray. Do not crack the tray about$600. to replace. So I just let the vacuum do the work. Sometimes small piece of insulation gets in mine. Its in the attic. I hope this works Good Luck

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