AC not working 100%. Should I call our HVAC foks?

[disneysteve]

It is currently 96 degrees with a heat index of 104. I noticed a little while ago that although our thermostat is set on 70, the actual room temp was 72. Uh oh. That's not good. The AC is running and is blowing cold air. I have a vent booster fan in our computer room that has a thermometer that shows the air temp coming from the vent and that's reading 57-58 degrees which is normal.

Does it sound like anything is wrong with the system or is it just so damn hot outside that the system can't quite keep up? The system was just fully serviced a couple of months ago including replacing some aging parts so it should be in tip top condition. I've been watching it for a couple of hours and it's maintaining the 72 degree temp. It just isn't getting down to the set temp.

Thoughts?

 

[target2019]

We're at 78 until sun recedes, then 77 until early AM. Both systems get time to complete a cycle.

 

[Jerry1]

I think you’re expecting too much. If my outside temp was over 100 degrees, I’d feel pretty good getting the inside temp below 80 degrees. I keep mine around 78 until evening (for bed time) when I turn the temp down to 76.

 

[disneysteve]

I think you’re expecting too much. If my outside temp was over 100 degrees, I’d feel pretty good getting the inside temp below 80 degrees. I keep mine around 78 until evening (for bed time) when I turn the temp down to 76.

Ours is always on 70 and it always maintains that temp, even during heat waves, so today is definitely atypical.

 

[Dtail]

Could be the start of something. The few times though that we set it that low, it had trouble getting there when outside heat index was at 110.

 

[Montecfo]

Exit temp normal. How is fan volume?

Might check coils and see if anything has frozen up.

If not I would be thinking thermostat.

 

[FindingForward]

It is currently 96 degrees with a heat index of 104. I noticed a little while ago that although our thermostat is set on 70, the actual room temp was 72. Uh oh. That's not good. The AC is running and is blowing cold air. I have a vent booster fan in our computer room that has a thermometer that shows the air temp coming from the vent and that's reading 57-58 degrees which is normal.

Does it sound like anything is wrong with the system or is it just so damn hot outside that the system can't quite keep up? The system was just fully serviced a couple of months ago including replacing some aging parts so it should be in tip top condition. I've been watching it for a couple of hours and it's maintaining the 72 degree temp. It just isn't getting down to the set temp.

Thoughts?

70 degrees when it's 104 index out there is asking a LOT of your AC. You did say it reached that with no problem before, so there's that.

I know commercial/industrial models can get a room freezing cold, even on the hottest day, but I know I never could with any of my home units over the years - the unit would literally never shut off and would probably burn out. I'm no HVAC expert, but when the temp is over 95, I won't set it below 77. But we live in an extremely humid area and in general, ACs have shorter life here.

74 would feel like pure bliss to me lol.

 

[Dawg52]

I would just watch it. As others have said expecting 70 when it's that hot outside might be a little much. I keep mine on 76 with a ceiling fan on low and it's very comfortable to me. I'm in MS and it's hot here too.

 

[disneysteve]

I don’t know how people manage at 76 or 78. I’d be a sweaty mess and no way I could sleep with it that hot. Maybe with an air mattress on the basement floor but definitely not in the bedroom.

 

[FindingForward]

I don’t know how people manage at 76 or 78. I’d be a sweaty mess and no way I could sleep with it that hot. Maybe with an air mattress on the basement floor but definitely not in the bedroom.

I hate it, but have no choice. Even if my AC cooled to that low a temp, the bills would be astronomical. They're pretty high now.

 

[target2019]

We might be different?

 

[GrayHare]

sounds normal, if you want it cooler, consider adding an attic fan, sun awning, and/or more insulation

 

[Aerides]

Does it sound like anything is wrong with the system or is it just so damn hot outside that the system can't quite keep up?

It's just that darn hot. Unless you want to invest in a bigger unit (not usually a good idea unless yours is undersized).

Look at things like windows, where the sun is baking on the house, any gaps or leaks, to improve your layout. Is your insulation good? Stuff like that. But no, your unit is working fine. In the heat of crazy times, it's going to run for a while and maybe not keep up, especially to be cold like 72. Mine has a hard time with 76 in these worst July days.

 

[disneysteve]

70 degrees when it's 104 index out there is asking a LOT of your AC. You did say it reached that with no problem before, so there's that.

That's my concern. 100+ heat index isn't terribly unusual here. We had it for a few days week before last and the AC was just fine. I'll keep an eye on it over the next 24 hours and see what happens.

 

[latexman]

Does it sound like anything is wrong with the system or is it just so damn hot outside that the system can't quite keep up?

It’s doing all it can do and losing ground during the hottest part of the day.

 

[Teacher Terry]

When our temperature is around 100 my condo ends up being between 78-80 by 4. I can usually get it down to 75 by 10pm and then gradually it gets cooler. Just impossible to keep up with extreme heat.

 

[CardsFan]

That's my concern. 100+ heat index isn't terribly unusual here. We had it for a few days week before last and the AC was just fine. I'll keep an eye on it over the next 24 hours and see what happens.

We get a lot of days like that, but we never set it that low during the day (73-75). Night-time, yes we go to 70F.

If it has handled this before, then I would check the inside filter, to make sure it is not too dirty, and I would check the outside coils to make sure they have good air flow. I always wash mine from the inside out, though some folks have good luck just washing down the outside. Cottonwoods were late this year near me, and they can plug a coil pretty good. If you just had it serviced they MIGHT have done these, but unless you saw them do it, I would not bet on it.

And don't forget, a bigger unit is not always better. Too large can cool you too fast and not get all the humidity. Then you get that clammy feeling inside. The ideally sized unit will run almost all the time on a record hot and humid day.

 

[jollystomper]

I would not worry about a 2 degree difference like that in this heat, Frankly I would probably set my thermostat up to 72, in that situation, to avoid pushing my AC too much.

We set ours at 76 for the summer. Right now here thermostat shows the outside temp at 95, while my weather station monitor has it at 104. After I have been outside for 10 minutes, coming back in feels ridiculously cool .

 

[5Miler]

We have seen our share of hot, humid weather this year living in the Atlanta metro area. We have two AC units for upstairs and downstairs, upstairs unit is about 12 years old and downstairs unit is 33 years old. The temps were a little better today only in the low 90s and both easily held 76 degrees which is our normal summer setting. The original upstairs unit used to have issues holding a good temp in the daytime until I finally gave up and replaced it 12 years or so ago. No issues since then. Just got the electric bill for last month and it was the highest I have ever seen since building the home in 1991.

Your temp differential between the cold air return and the vent seems fine so I agree a check in airflow seems in order. Possible filter change needed or something related. It might be worth your while to have the system checked once more by a technician. My home is 33 years old with single pane windows and takes lots of direct sunlight due to several large trees I've had to have removed the last few years.

 

[Texas Proud]

Your system might not be sized to get it down there... but if it has done so before with no problem you should call...

My last house the AC guy said my system was designed to lower the temp 30 degrees... so when it got over 100 my temp would go over 70 even if the AC ran 24 hours a day...

 

[disneysteve]

I would not worry about a 2 degree difference like that in this heat, Frankly I would probably set my thermostat up to 72, in that situation, to avoid pushing my AC too much.

That's a good idea.

 

[disneysteve]

I did just change the filter a couple of days ago so I know that's okay.

 

[GrayHare]

btw, the humidity part of the heat index has no impact on the operation of a residential A/C system, so instead reference the ambient air temperature shown by a thermometer in the shade

 

[disneysteve]

btw, the humidity part of the heat index has no impact on the operation of a residential A/C system, so instead reference the ambient air temperature shown by a thermometer in the shade

Would the humidity level inside matter? If it's more humid in the house, would it be harder to cool? I did just lower our dehumidifier yesterday because my wife and daughter said it was too dry in the house.

 

[GrayHare]

Would the humidity level inside matter? If it's more humid in the house, would it be harder to cool? I did just lower our dehumidifier yesterday because my wife and daughter said it was too dry in the house.

Higher humidity might feel worse to people, but a home A/C unit lowers the temperature virtually the same at any humidity level.