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

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

Is it normal with a mini split to see evaporator temperature difference much greater than 14-20 deg F? If so why? We have a 24K BTU mini split for a 900 sqft building, one season old. I am seeming evaporator input and output air temperatures difference as large as 40 deg F with full fan, turbo fan may decrease the temperature difference a few deg F. The condenser and evaporator coil and filters have just been cleaned. With the fan set on maximum speed. Unit set temperature 70 deg F, input air 86 deg F outside temperature 102 deg F, out put 37-40 deg F,input temperature 78 deg F output difference 35 deg F outside temperature 97 deg F. With night time temperatures of 80 deg F the input 76 deg F, output 25 deg F lower. The due point has been running close to 77 deg F at night and about the same during the day. Steady drip of water out of the condenser line during measurements. Used type K thermocouples for measurement not IR unit. The input and output lines on the condenser are both condensing water so they must be below the due point.

How long do it take when your house is on 92 degrees in your house

Hi, I have a 2.5 ton water source heat pump for 1030 sqf condo that runs all day when I set the thermostat to 73. Air coming out of the unit the lowest has been is 62. Which is not way near the 20 degree delta. I had the unit flushed and cleaned, but it didn’t help. What could it be?

My senior apt. has a heat and ac GE unit put in below window. Sometimes the air coming out is in the high 30's or low 40's. It has remote control which maintenance has. It is used to constantly change how this unit runs. I know there is a way I can change it from the panel of the unit, but the maintenance man that would raise the air temperature has left. Could u tell me how to do it..the model is AJEQ12dcf. I am 82 and the cold air burns my skin. When they put it on 53 degrees it is fine. Thank u so much if u could answer me.

HI, I live in the desert where it's currently 109°F outside. Right now, the air coming out of the vent closest to the air handler is around 52°F and the house overall is around 72°F. It's a split heat pump using R410a however I don't know if the evap and txv were ever changed when the R22 system died. Are those temps pretty good? Compressor is drawing about 20 amps as I type this. Rated at 21.5 on the label. Thanks for making yourselves available for our little issues and questions! Paul in the desert.

I just had my central Ac unit service big time. The oils needed to be cleaned in the air handler it was covered in white algae that should have fixed the problem, the air is blowing out, but at 65 degrees and the air flowing up to the return is 77 why is the air not cooler? refrigerant is fine, air flow is good. This is my problem. It will not cool below 77 in my house If, I have the thermostat set at 76 by noon it jumps to 78, I turn it up to 77 and it drops to 77, by 3 pm the temp jumps up to 79 I turn the temp to 78 it drops to 78, by 5 is will go up to 80, I raise the temp to 79 it drops to 79. I try to turn it down at 10:30 at night and it wont go below 77. what the hell could be wrong? Service calls are expensive....

thermostat set to 71 temp shows 85. When we check the temp coming out of register is is like 50 something. I know the thermostat is not broke because it is burning up. Any ideas what could possibly be? Landlords say since it is 50 something coming out of the vent that there is nothing wrong but obviously there is. Thank you.

I know these guy are experts, should know more than me. But I don't see how a air temp out of a duct should be a hard, fast 20 degrees cooler all the time no matter what, as they suggest. Right at my vent, my air temp right out of my vents is about 48 to 50F regardless of the outside air temp or what setpoint I have my thermostat set at! And I live in Utah where it gets to 100F or more all the time in the summer. The temp in your house is controlled by the time period of how long the air is blasted out of your vents, or how long the air conditioning runs in a given period. No A/C unit I know of actually controls the air temp blowing out of it. It's all done by time period. The hotter it is outside, the longer in a given time period your unit will have to run, just that simple. The actual temp is probably more due to how much refrigerant or freon your unit is charged with. AC systems just don't control actually air temp out of them, it's just supposed to be cold air, period.. Unless there are newer systems out there that I don't know about.

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..

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.

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

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.

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

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

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

Thanks for the advice!

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

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!

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.

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

very informative and helpful

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.

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

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?

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??

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.........??

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?

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....

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.