An air conditioning question.

The temperature has been in the 90s and 100s for weeks, and will continue.
The A/C runs constantly during the day. At night the temperature drops into the seventies. Should I turn the thermostat up so that the compressor will shut down for a while at night?

It shouldn’t have to run continuously to maintain a reasonable temp inside.

You should call your A/C repairperson.

Set it for the temp you want and let it do its thing. It only has one job!

No kidding. Are you leaving your windows open or something?

My neighbor is an A/C guy. He told me a story of a dude who had a stereo or something sitting right underneath the thermostat that was always left on and generated a bunch of heat. The guy calls Dave to find out why his A/C runs all the time.

Your A/C is either of inadequate capacity for the area being cooled or it’s in need of maintenance, or you have serious issues with the ducts, insulation, and/or window&door seals.

This. A hundred times this.

The calculation for the required AC capacity is quite lengthy and involved. Few people do it. When a unit needs replacement, they just get a new unit of the same size.
The calc involves room size, window size, which direction it’s facing, and more - much more.

If the vents and ductwork are in good condition, the coil may need cleaning, the compressor may be failing or just blocked. Clean any filters and check the compressor to ensure it has adequate air flow.

At night, when the outside temps drop OPEN THE WINDOWS. Free cold air trapped inside before the sun comes up will do much to help.

It was 102 F earlier. It is now 76 and dropping. 61 is forecast overnight.
I will open doors and turn on floor and ceiling fans. At least the bedroom will be cool when I awake.

Indeed, we did it in an undergraduate class.

Ya’ll obviously don’t live in Arkansas. Open the windows overnight? It’s stills muggy as fuck at 2 am, and then the ac has to remove all that moisture you let in overnight, as well as cool the place down.

The ac is supposed to run for long periods in the summer to allow it time to dehumidify. Oversized units are more of a problem than undersized, for this reason.

Is it maintaining the set temp?

Related I hope…

It dawned on me the other day that if I ran the fan constantly I could get the cool basement air up into the main floor. I thought it was working great!!! … until I realized that the A/C was still running no matter what.

I called my HVAC guy who remembered that the wiring in my older house was limited so that he couldn’t set the fan up to run on its own. I asked whether my strategy made sense such that we might want to fix the wiring. He advised against it (said he had tried it himself) because it would cause more condensation in the basement.

But now that I think about it…seems like the basement is generally more humid than the upper/main level anyway. Wouldn’t circulating the air help rather than hurt?

Thermostat at 70, it keeps 73 at 95 outside.

Something’s wrong; call a service tech.

Yeah, but in the meanwhile, the “correct” setting of your thermostat when it’s that hot out would be 74 so that you at least cut your poor, beleaguered A/C a little slack. Not much point setting it at 70 if you know it can never get there.

Not necessarily. One can really only expect a 20 degree differential between outside and inside temps. Many contractors will only “guarantee” a 15 degree differential. Here’s one cite, of many:

If the unit is maintaining 73 inside and the outside temp is 93 or above, it’s doing the job. If I were the OP, I would set the unit for about 20 degrees lower than the expected high for the day and slowly adjust from there until the unit cycles off occasionally.

I set it to 75 at night, and it occasionally comes on.

A/C in the deep southeastern U.S. is a different animal than it is in much of the rest of the country. We have to be resigned to replacing A/C units (at least condenser motors) more frequently than in the Midwest and Northeast … because for 5-6 months out of the year down here, it MUST run 21-22 hours a day. And a unit big enough to run only, say, 16-18 hours a day leaves your home very humid and uncomfortable, even at 70 degrees inside.

A/C units have to run a lot in the winter, as well. Down in the N.O. area, it feels hot/humid enough to run the A/C anytime the outside temperature is above, say, 60-65 degrees. Some people do, in fact, open windows and deal with the humidity at certain times of the year to save money. But during the summers … it’s almost never done.

There is no appreciable cool air at night in the summer. Humidity is too high, so it feels sticky … and it’s still around 78-82 degree air.

Living in brand-new construction with up-to-date ductwork and insulation helps alleviate some of this … so maybe your A/C runs, say, an hour or 90 minutes less per day. However, there’s a lot of homes built in the 1950s-70s and even earlier … and in those homes it costs big upfront bucks to make the climate-control efficiency comparable to a new home.

I called Mrs. Plant (v.2.0) from Arkansas in New Hampshire in October, and mentioned that I had to run the A/C in the car. She cried.

This might be your answer right there. You’re keeping the house 22 degrees cooler than the outside air and running as much as it does, you are removing tons of humidity.

Try setting the stat at 73 or 74 and see if will shut off a bit AND keep the house as comfortable as it has.

You didn’t say you were uncomfortable, and you’re in a hot, humid part of the country, as am I. The unit has to run a LOT to remove humidity but I don’t think it was designed to get to 70 degrees on a 95 to 100 degree humid day.

Down here, having a car without A/C is little better than not having a car at all :smiley:

My pick-up truck has broken A/C. You can get used to a lot, but no A/C in your daily driver sucks out loud.

Not sure if this helps, but if your overnight low is going to be around the same temp as what your a/c is set for, then it isn’t going to run much overnight. As a consequence, the humidity is going to build up and you’ll wake up sticky. Your choices are to lower the thermostat so that the a/c will come on more and keep the humidity at bay or turn it off at night and open the windows.

We had a close one yesterday, got up to 89. We haven’t cracked 90 since Sept 2013, hoping we can keep the streak of under 90 going.

Amen to this. If anyone had told me to open the window in July when I lived in Florida, I would’ve hit them. It’s muggy and sticky and awful.

And now we have the same gorram weather in Massachusetts this week. Ok, a tiny bit less humid, but still rotten. And the a/c in my condo was obviously put in by a builder who thinks it never gets hot here. My upstairs bedroom is hotter than hell and muggy, even with the other vents mostly closed. It’s sucky.