See if you can spot any ice on the lines on the inside and outside unit. Chances are the coils are frozen. You will need to let it defrost if this is the case. Could take up to 24 hours. Or less than an hour of you run the heat. Be prepared for water to leak from the inside unit as the drain may not keep up. Once fully thawed (you’ll never know when unless you can see inside an access panel, so longer is better) you can run it again. You should change the filter as low air flow can lead to frozen coils. If it happens again with a fresh filter, chances are it has low refrigerant and needs to be charged by an HVAC tech. If it’s low after one year, you probably have a leak somewhere. Hopefully it’s under warranty still.
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That’s definitely too hot for a brand new AC, was it rated for a dwelling of your size? Mine is almost 20 years old and keeps my 1800sqft home in the mid 70s at 100 degree outside temps
This is how I fixed mine when it happened to me. I didn’t realize the AC was using the same air filter as my furnace, so it had gotten really dirty and blocked airflow. A cheap new air filter replacement fixed all the issues.
Many good suggestions, but I didn’t see anyone bring up how well the house is holding the temperature, aka insulation or leaks. The best AC can’t keep it cool if that cool is going outside somehow. You say the vent air feels cold so it seems to be doing its best. Single pane windows, especially facing the direct afternoon sun will be hard to keep from undoing the cooling. Attic space that has little insulation will also defeat the efforts.
Yep, always my first thought. If you’re in the US you can get tax benefits by making your home more energy efficient. It’s doable yourself but hiring someone to do it will eventually pay for itself.
And for the attic don’t just pile on insulation, need a good air sealing first if that’s no good.
This. Lack of insulation, leaky doors and windows, etc. will give your system a lot of load. My sister has no insulation and her electric bill in the summer is double mine, and I live in a bigger house.
As others have stated, replace your air filter if you haven’t recently. Make sure it’s the appropriate size and rating. It should probably be pleated, and the MERV rating shouldn’t be too high unless you know the fan supports it.
Use a temp gun or a kitchen instant read thermometer and compare the exhaust temp vs the return temp. It should be around 15 degrees difference or more. If it’s not then an installer should adjust the pressure on the system.
If you have multiple floors you may have a vent damper for summer vs winter. In the winter the dampers may be set to help force air through the lower floor vents and prevent the hot air from rising too fast to the upper floors. If the installer or previous owner was nice the damper will be labeled for summer vs winter.
If it’s not blowing air at all, then you may have a leak or a blockage.
If theres ice on the indoor coil or on the lines outside then either the filter is clogged or your pressure is off.
If your hvac person is telling you it’s working fine and it obviously is not, call a different installer.
when this happened to me the heat exchanger inside was all iced up, turned out it was a valve in the circulation. Couldn’t fix it myself due to compressed coolant.
1400sqf = 130m2
Typically in Australia we’d size for 180W/m2 which in a domestic setting gives plenty of heads room.
130x180 = 23.4kW unit. This size it would be a ducted unit to ensure proper distribution of cooling throughout.
2.5tonne equates to approximately 8.8kW which only gives you 68W/m2 which as an ex mechanical engineer is completely undersized at least for Australian summer.
Without knowing more the only suggestion I would give is set the target temperature a bit higher. This increases the units efficiency and should help it get to temperature quicker.
If you’re uncomfortable try running an additional fan. The movement of the air will make you feel cooler even if the air temperature is the same.
Has it been working alright throughout the rest of the season? I had an HVAC system that was incorrectly wired by the installers, so it actually ran the AC and heat pump at the same time, cancelling each other out. Might not be your situation but you never know!
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That could be part of a problem if it isn’t circulating.
Make sure all the vents are open and not blocked by something inside. Switch filters if you haven’t recently, and make sure they are the right kind for your unit. If you can get to your duct work, see if it is leaking anywhere as that will reduce the pressure at the vents.
If you have ceiling fans, turn them on to help out. If you aren’t already, close curtains to block direct sunlight (east side in the morning, west in the evening).
I would recommend having a different company check it out since they won’t be defensive about the prior work.
You can’t “run the heat pump and a/c at the same time” because it’s a single unit. There’s a valve that slides when powered to switch the hot side with the cold side. That’s literally the only difference between a/c and a heat pump.
You are correct, but they probably have backup electric heat. Heat strips were being engaged along with a/c.
2.5 tons is right in the edge of being able to handle 1400 sq ft. Where do you live? It is two story or one? I think your AC might just not be about to keep up. Nothing wrong with it.
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Growing up in the southeast, every AC unit is too small.
Something to consider would be a portable/window unit to compensate in high traffic areas/bedroom. Used to use that to cool a room and let the rest of the house run a bit hotter instead of fighting the outdoor heat.
The other posters have given good info. I just wanted to add to try setting the fan to on instead of auto so it runs all of the time. This will help keep the air moving in the house and might help keep it cooler. Also make sure you check the filter and change it if you haven’t yet. See if your energy company offers an energy audit. that will tell you if you have leaky windows, doors, or insulation problems. I have shitty insulation but with the ac fan running all of the time I can keep the house @ 70 - 72 on a 95 degree day.
I’d also consider getting a second opinion from another HVAC company, you could have undersized ductwork or another problem that the first company isn’t acknowledging.
Two issues with running the blower all the time. One, wear and tear on the blower over time. More importantly though, the coils in the unit need occasional downtime to let moisture drain for best efficiency. Your points on moving air while not cooling are valid though, and newer thermostats do have a circulation mode that will cut on the blower for a percentage of the time the AC itself isn’t on to do move air around. Good for second story homes with one AC, as the thermostat is usually on the first floor while the heat rises to the top floor.
Yeah. I only do on all the time when the air quality is bad. So basically the first time ever this year with the wildfires.
Have you replaced your filter recently?
Does the unit have a standard 1" thick filter or a thicker one?
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Could be a refrigerant leak. It will still run but won’t cool.
Take a look at your return register. I was having this issue at the beginning of the season and my return had some pet hair lodged in it. That coupled with a new filter (and for the return if it uses one) should help keep the temps down.
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I’m a layman but from what I’ve read recently, 92 to 78 is 14 degrees; the typical temperature differential is a maximum of about 20. There may be a few more degrees you can eke out, but you are getting a majority of the potential benefits
There really isn’t any such hard limit on systems like that.
While correct, you usually see only a 20 degree difference, that’s between the intake and exhaust. Since it’s recirculating the air that should be able to bring the cooled air down further.
I’m surprised no one mentioned this so far: check to make sure the fins on your outside unit are clean.
My parents had this issue when I was visiting. I went outside and looked at their unit and it looked like it was covered in carpet. I took a hose and gently rinsed off all of the dirt and pollen and they were back in action.
Others already covered a lot of good points: make sure it’s not froze (it likely is if you’ve been running for a while and it’s not keeping up) and change the filter.
If that doesn’t work you likely need refrigerant.
leaky ductwork is often a source of efficiency loss. i found a disconnected section of ductwork in my attic. Fixing that was a huge help.
