YSK that if you have an air conditioner you should turn it on before you need it.
YSK because the first hot spell is when most people discover their AC unit is broken.
Several years ago I waited to turn on my AC. This is how I found out about one of the busiest times for repairmen and had to sweat for two weeks. Now I do a test run a couple of weeks before it heats up. Same goes for the furnace at the end of Autumn.
Relatedly: there are HUGE tax credits for heat pumps right now; I’m actually paying several thousand dollars less for a new heat pump than I would have for a new central AC. (Installed as a two stage system, so I can still use my regular boiler when it gets cold)
So if anybody else is up for a replacement you should definitely take a look at any federal + state + local credits you might get for going that route.
Having a boiler + heat pump would be a Hybrid system. A 2-stage heat pump typically refers to the capability for the heat pump to run at lower power (such as 70% max) or full power, to try and prevent thrashing on slightly warm days, while keeping capacity available for hot days.
I'm just saying it's better for the units to run once in a while, and to test them to know they are still working. I guess you could technically run a window unit for a few min when it isn't in the window but watch out for condensation drain.
Refrigeration tech here. Don't run your home AC in the winter unless it was specifically designed for that. I think the person you're responding too was assuming that because that's what you're supposed to do for cars that you should do it for your home too.
In cars the AC compressor runs off the belts so there is a shaft seal that can dry out and crack if the system is not run every so often. On residential AC systems the compressor is run by an electric motor that is sealed inside the compressor housing. There is no shaft seal that can fail. Running your home AC in the winter can actually damage it if your system wasn't designed for cold weather running. When it's cold outside liquid refrigerant will tend to condense inside the compressor. When the compressor starts in those situations it will immediately suck in and try to compress that liquid refrigerant. Unless you're a physicist, liquids are incompressable. So you now have your compressor trying to compress something that can't be compressed. This is not good for the compressor to put it lightly. The best case scenario here is the compressor manages to force the liquid refrigerant out adding a whole lot of premature wear in the process. The worst case scenario is that something inside the compressor goes pop and it dies.
On systems designed to run in cold weather there will be a little band heater on the compressor to keep it warm and prevent refrigerant from condensing inside it. However that is not the norm for residential AC just because most residential AC systems don't need it and it would just be a waste of electricity.
Most machinery lasts longer when you run it every month or so at least. For an AC unit there is lubricant in the refrigerant, so circulating the refrigerant once in a while keeps the seals in good condition. It would also keep the moving parts of things like fans from corroding and seizing up.
For vehicles, running the them occasionally circulates the fluids like oil and antifreeze. The oil keeps the moving parts of the engine coated and doesn't allow things like condensation to rust the internal parts.
Second this. Keeps the unit in good order, you find out about issues before they become major problems, and it's usually fairly cheap like 50 bucks. The downside is it's a good opportunity for an unscrupulous tech to overplay some minor issue to try convince you to upgrade.
We did that last fall, turned it on on a hot spring day and it promptly died. (Thankfully it was early enough in the season that we were able to get a reasonably priced installation for a new one at the end of June).
We have our Aircon cleaned around March or April because when everyone turns them on and realises how badly they smell in July all the cleaning services are busy.
YMMV But another fun AirCon fact*.
A few years ago we switched from running the air con hard at 20°C or so when we got home, having it turn off automatically late at night, running it hard in the morning and turning it off when we went out...
To....
setting it at a supposedly "high" setting of 27°C and leaving it on 24/7 (July to September)
The running cost was the same and it was very comfortable coming home to an already cool dry environment. We never felt the need to lower the temperature either. It was lovely.
*"fact". I'm sure the condition of your home insulation, outside temperature and conditions, draftiness of windows and doors etc all play a role.
It was probably running R-22 which you can still get but it isn't manufactured anymore. It's ozone depleting so all production and import of the stuff was completely banned in 2020 and it has been in the process of being slowly phased out since 2004. The only source for it is stuff recovered out of other systems or any existing stocks which are running out very quickly. That means it gets more expensive every year. Now a days most HVAC companies will just replace those systems rather than fixing them for that reason.
This is true of car ACs as well. Many modern cars with climate control do use the AC to some degree in defrosting, but some use periodically will keep seals from drying out and causing leaks.
Yup, what we learned here. Our air is working fine as we did get a new one not too long ago. So need it during the summer time around here in the midwest.