How Cold Should The Air Be From My Air Conditioner? - Ask the Expert Episode 169

A good air conditioner will blow nice cold air, but is there a standard temperature at which air should be blowing from the air conditioner?

Video Script:

Today's question is from Paul. "Hey Dan, what is the ideal air temperature from a properly running ac unit?"

I guess that depends on what you mean. If you mean, what temperature should the air coming out the vent be? That will depend. If the AC system is operating correctly, then the air coming out of your vent should be about twenty degrees cooler than the regular temperature inside. So, if you're cooling it and the house is 80 degrees, then you would ideally want the air to be about 60 degrees.

Have more air conditioner questions? Just ask them in the comments below or on Facebook or on Twitter.

40 comments (view/add)
  • Diane
    Diane
    Posted on 10/15/2021

    Inspector (for a sale) says return air is 77 deg and air supply is 68 degrees, a 9 deg differential and said should be 20. What are the possible problems. Tech coming out Monday but your thoughts might help me get through the weekend without too much worry..

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 10/18/2021

    Without knowing the system specifics, I can only speculate. Low charge is one of the first suspect items. If the system is not set for correct air flow, that can also cause a low differential. The only way to really know is to have a tech come out.

  • Jim
    Jim
    Posted on 10/9/2021

    The air temp coming from the duct is 65 degrees. Outside temp was around 90 degrees . Is that acceptable or should I have the unit checked? I keep the thermostat it 78 degrees and it seems to work hard to keep that temp.

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 10/11/2021

    The temperature differential between incoming and outgoing air at the air handler should be approximately 20F. If the air coming into the indoor unit is 85F, then 65F outgoing temperature would be right. Otherwise the unit should be looked at by a technician.

  • Sharon Kramer
    Sharon Kramer
    Posted on 7/26/2021

    I live in Northern Iowa which is zone 5 or 6 just got a new air conditioner and furnace. The tech that put it in put in a two and a half ton air conditioner my house is a split for your house it's about 800 900 ft on the top level and I don't know if they just double that or if they do half of the upper level square feet. But my house was freezing and he came back and put in a 2-ton which is better but the fan speed seems to be very powerful and I had asked him about if it needed to be moved down and now I'm just wondering if the furnace maybe is oversized for my house as well as the air conditioner was. What would you suggest as far as the tonnage on air conditioner and the BTUs on my furnace as far as what is the correct size. I have put in more insulation in the Attic and my windows aren't new but they're pretty tight they're like a double or triple pane windows. Hopefully you can help me thank you

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 7/27/2021

    Long distance estimating HVAC requirements is fraught with error, so I am always reluctant to do it. If you're not convinced you have the right size, get a second local opinion. Alternatively, find an engineering firm that isn't selling you HVAC equipment that can do a Manual J load calculation. Then you will know exactly what you should have.

  • Nomi
    Nomi
    Posted on 7/22/2021

    I just got a new ac unit WA1442CJ1NA. Ac tech installed it. I just noticed that the temperature of the air from the supply vent is not cold enough. So I called the tech who installed it and he measured the temp and it was showing 68 or 69 on the ac vent while the thermostat was at 73. So he went outside and said that freon was too much and took put some freon and then measured the air temperature again at the supply vent and this time it showed 58 which is a good thing and I was happy that it was cooling properly. Then after a few hours, I started to have issues again. The air temperature in the supply vent again showed 68. Do you know what could be the issue this time? I have new evaporator coil in the attic and a new condenser outside. I m just worried what should I do now.

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 7/23/2021

    There are several possibilities, but most likely the charge is not right. Assuming that the correct orifice piston was used in the coil, the charge must be adjusted according to a superheat table. If the system uses a TXV, then the charge must be adjusted according to subcooling and should be 9F or so.

  • Tara Leatherdale
    Tara Leatherdale
    Posted on 7/4/2021

    My thermostat is set to cool to 72 degrees F however when the ac is on I checked the temp coming out of the vent and it reads 58.8 that is only 13.2 degree cooler. Is something wrong with my ac unit ? I have a 2.5 ton with micro channel coil. Freon is fully charged and vents in unfinished basement are closed. 2 story 1676 sq ft home. The vent I checked is on the main floor. Please help

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 7/12/2021

    Yes, there could be something wrong. You should have a technician come out and examine the system.

  • Tara
    Tara
    Posted on 7/2/2021

    It is currently 98F outside, I have my AC set to cool to 70F. Home is currently at 71F ac has been running for 2 hours...temp coming from the vent is 58.3F. Is this normal since you said the temp coming from the vent should be 20 degrees cooler than temp in house. I have a 2.5 split York ac unit

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 7/12/2021

    Your differential is 13F, so it would be a good idea to have a tech come out and examine the system.

  • Wayne
    Wayne
    Posted on 7/1/2021

    Ac cools fine doesn't shut off at set point keeps cooling. Duct temp gets to 43 degrees so I shut down unit before it freezes up.why does this happen

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 7/1/2021

    It could be a bad temperature sensor. The only way to know for sure is to have a technician evaluate the unit.

  • Dawson
    Dawson
    Posted on 6/29/2021

    Thanks for the advice!

  • Jeffrey Seibeck
    Jeffrey Seibeck
    Posted on 6/26/2021

    My vents blow downstairs when my upstairs vents are blowing. But when my down stairs turns on it only blows downstairs . Ac man came yesterday and said it was fine. Can u help.please

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 6/28/2021

    If your installer says your system is working as intended, I'm not sure how we can help.

  • Steven Storey
    Steven Storey
    Posted on 5/5/2021

    I have a Home A/C I think it's a 3-ton unit (Model # CA15NA036-A) which is blowing about 82 degree air from it's vents after running for 1-1/2 hours when I have the temp set at 72. The system came with the house which was bought new in 2015 and worked fine till the fall of 2019. My first question is: is this a central air-system or a heat pump and how can you tell the difference? It worked fine last summer. During the winter I ran the heater for probably about 3 months at nights (hot air comes out of the same vents as the A/C). In 2018, I had a patio installed which required cutting the a/c lines in order to move the compressor / condenser unit so the patio could be installed, then it was re-installed back to the original location (now maybe 3-4 inches higher) and the cut lines were re-soldered. At the time, the a/c guy somehow damaged the low-side service valve possibly during his re-soldering efforts which caused it to leak. He then decided to use "Nylog Blue" which is some kind of a/c system sealant which he used to re-seal the damaged valve which was more-than likely a bad o-ring. My question is what could be the problem since this has been working fine since 2018. You mentioned to another person on this blog that was having cooling problems that "It could be low on Refrigerant again". My second question is do the a/c systems lose refrigerant over a period of time normally and just need to be "recharged" every few years? I'm an auto tech and I've seen a/c systems in cars still blow cold air with the original factory charge for well over 10 years from when the car was built, and they have to go through a lot more movement and vibration than a home system. If it isn''t normal, what could be the problem with my system and what would I be looking at price-wise? Thanks for the help!

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 5/6/2021

    The CA15NA036 is an air conditioner. The easiest way to determine whether or not a unit is an air conditioner or a heat pump is by just looking up the model number.

    As to the rest of your question, an air conditioner (or heat pump) can stop blowing cold is due to a refrigerant leak. Are leaks normal? No, but they're one of the more common recurring problems that an HVAC tech will see. The proper isn't movement or vibration. The real culprit is typically corrosion due to poor maintenance/cleaning. Your system is obviously not working properly. Is that due to low refrigerant or something else? Hard to say. The thing to do right now is get a professional to inspect the system, because it should definitely not be blowing 82 degree air.

  • David
    David
    Posted on 4/28/2021

    I have a brand new Merit Series, Heat Pump with Quantum Coil, 2.5 Ton, 15 SEER, 1 Stage, 1 Phase, R-410A, I have a question. My set temp is at 73. But I only get 61 air temp supply. ( using temp gun)I was reading that incoming air should be 16-21 return air difference. Also called delta T , just wondering if this is normal air temp coming out of the vents. Reason I’m asking I had an issue at the beginning where they found it to be a low refrigerant one time. So wondering if my unit still good or not.

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 4/29/2021

    By temperature gun I assume you mean an infrared thermometer. Those do okay, but the temperature reading isn't always super reliable when it comes to the HVAC business. The best tool is a digital HVAC thermometer. Those are a little pricey just for checking your home air vents. However, you could get an in-duct thermometer that will give you a much more reliable reading. You can find a good one for about $40.

    But the real test is whether or not your unit is keeping the interior cool. If it's doing the job, I would worry about it. Keep your air filter clean, schedule the annual maintenance, and it should be fine. Of course, if it's not hitting the set temp, yeah, it could be low on refrigerant again.

  • Joseph Glenn 111
    Joseph Glenn 111
    Posted on 9/8/2020

    How come the temperature coming out of the A/c Vent is 20° cooler than the inside temperature and the house does not cool and the a C runs all the time

  • Kyle
    Kyle from Ingrams
    Posted on 9/9/2020

    The unit you're using could be undersized for the space. Or undersized for the space in relation to how hot it is outside. If you're experiencing extreme temperatures, the unit might just not be able to keep up.

  • Nafees Rehman
    Nafees Rehman
    Posted on 8/28/2020

    very informative and helpful

  • Charlie Frank Gude
    Charlie Frank Gude
    Posted on 8/26/2020

    What is the reason that AC systems only average 20 degrees lower than ambient temperature? Who set this "20 degree" standard in the industry or is it a limitation based on refrigerant gas.

  • Kyle
    Kyle from Ingrams
    Posted on 8/28/2020

    In general, it is a limitation of the specific refrigerant. It can also be affected by specific system design.

  • Kurt
    Kurt
    Posted on 8/21/2020

    Thanks for the explanation. My a/c went out and the professionals fixed it and it’s like 92 in the house. I shot the vent and was only getting like 72. Which in you expiation that would be correct. I assume as the house cools it self the temp from the ac will also come down. Thanks for the great explanation

  • kurt
    kurt
    Posted on 8/3/2020

    My laser temperature air thermometer is reading 35 degrees coming out of my ac vent into the living room. Is that possible, or is my thermometer not reading properly, and must not be calibrated properly?

  • Kyle
    Kyle from Ingrams
    Posted on 8/3/2020

    In general, infrared (laser) is not suitable for HVAC work. The 35F reading is next to impossible for a standard AC system. A standard HVAC thermometer (under $10 at the auto parts store) will give more reliable results

  • marty pethel
    marty pethel
    Posted on 8/2/2020

    I have a brand new heat pump. My a/c guy say's it's properly charged, although I don't think so. When my house is at 72, the air coming from my vents is 58, and runs all day to keep it there. I have a window unit I turned on with the same house temperature at 72, and the window unit immediately goes to 42 degrees. Why can't my heat pump a/c do that??

  • Kyle
    Kyle from Ingrams
    Posted on 8/3/2020

    If your new heat pump is maintaining the interior temperature, I'm not sure I understand the issue.

  • Martin Moebius
    Martin Moebius
    Posted on 8/1/2020

    How cold or how low can or should the air coming out of the home central air vent get at the very coldest if running full blast and if brand new unit? 46, 48 ,50 degrees.........??

  • Kyle
    Kyle from Ingrams
    Posted on 8/3/2020

    The vent air temperature is relative to the outside air temperature.

  • Nora Wheeler
    Nora Wheeler
    Posted on 7/12/2020

    How cool can it actually get the air? If your house is already at 72 degrees, will the AC still get it down to 52 degrees, or is there a lower limit?

  • Kyle
    Kyle from Ingrams
    Posted on 7/13/2020

    Every air conditioner or heat pump will have a minimum temperature setting. Plus, the hotter it is outside and the less insulated your home, the more difficult it will be for any air conditioner to maintain a very low temperature.

  • martin porter
    martin porter
    Posted on 7/4/2020

    come on..... there could be claim that could be made for a "properly installed and operated HVAC residential system for the temperature of the air delivered to an interior vent be 'X'. yes the temperature of the attic heat could be considered, and yes, the ability of duct work to supply (or transfer) cool air to the vent box from the plenum where a known actual temperature "X" of air inside the plenum is known or a known temperature of air "X" coming across the coil....

  • Larry Butler
    Larry Butler
    Posted on 6/22/2020

    How can you tell if your compressor is working correctly on split unit, I don’t think mine is cooling good enough. The copper pipe coming out of compressor is about 67 degree on a 2 ton split unit.

  • Kyle
    Kyle from Ingrams
    Posted on 6/23/2020

    If you think your equipment isn't working properly, you can contact our Warranty & Tech Department at 270-575-9595 x300.

  • GREGORY S LAPRETE
    GREGORY S LAPRETE
    Posted on 4/3/2020

    My thermostat says 79 i set it to 60 but the air is only coming out at 75.5 any ideas?

  • Kyle
    Kyle from Ingrams
    Posted on 4/6/2020

    Definitely need more information. Give us a call at 270-575-9595 x300 to speak with our tech department. We'll try to help you get to the bottom of this.


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