Is the A/C broken cuz it HOT in herr!
July 18, 2006 1:08 PM   Subscribe

A/C filter: Is mine broken or is it just because it's 100 degrees outside?

It's really hot around here. Over a hundred the past couple days. The air conditioner (central heat and air, NOT a window unit) in my house has been running constantly yet it never gets below 80 degrees, except for between, say, midnight and 5AM.

It is set on 75 during the day. My dad says it shouldn't get 5 or more degrees above what it's set to. But it is blowing out cold air, which is the first thing he had me check.

So. Should I call a repairman or just chalk it up to waaay hot days right now?
posted by CwgrlUp to Home & Garden (23 answers total)
Set it to 70 and see what happens.
posted by defenestration at 1:17 PM on July 18, 2006

I would call a repairman. I have central air and it's not even on constantly, and it's been nearly as hot where I am. Think about how much you're spending in electricity to not get a cooled house!
posted by sugarfish at 1:17 PM on July 18, 2006

Central air should be able to cool down your house.

Is the area near your thermostat cooler than the rest of your house? Are any windows open, or doors to areas that don't need to be cooled open (e.g. basement, garage doors)? Is anything obstructing the vents? If you're sure the cold air isn't leaking out into areas you don't want to cool, and there is nothing that would make the thermostat think your house is cooler than it really is, then you should call in a repair person to take a look.
posted by tastybrains at 1:18 PM on July 18, 2006

We have the same problem when it's very hot outside--our unit simply can't handle the amount of work required. We've supplemented our central system with a window unit in the bedroom.
posted by MrMoonPie at 1:18 PM on July 18, 2006

We've done exactly what MrMoonPie has, here the heat and humidity are so oppressive in July and August we've had to get a window unit for our upstairs bedroom. The downstairs is fine, it's the upstairs that's hard to cool.

Then again, I'm famous among my friends for always having the coldest house around-I'm always hot.
posted by hollygoheavy at 1:20 PM on July 18, 2006

In my neighborhood, teenagers somehow steal the freon out of ac units to get high or something. It is very strange, but it has happened several times on my street. We had to have ours replaced, or refilled, i guess, and I believe it cost a couple hundred dollars. Without freon, the AC still blows in the house, it just isn't very cold.
posted by foxinthesnow at 1:22 PM on July 18, 2006

Sorry, I didn't quite finish my comment. You might want to ask your neighbors if their AC doesn't seem quite cold enough, either. It could be freon theft!
posted by foxinthesnow at 1:23 PM on July 18, 2006

It is probably a case of frozen coils. Water from all this humidity condenses and freezes on the coils inside the furnace. Ice is a great insulator; that is how igloos work. Turn your fan on and AC off and let warm air blow over the frozen coils for 30 to 60 minutes. If that was your problem you should start getting colder air out of the unit again. Of course it could just be so hot that it is beyond the capacity of your AC unit. A new filter couldn't hurt. If the filter is really dirty of course that will dramatically cut efficiency, but if it is just a little dirty a new one will at least help a little bit.
posted by caddis at 1:24 PM on July 18, 2006

Have you tried cleaning the little metal "fins" on it? Here in Missouri, the cottony stuff from cottonwoods clogs ours up and causes it to do EXACTLY the same thing. We either have to hose it off with a garden hose or blow everything out with an air compressor.

In fact, I need to clean it out now because it's not getting below 80 in here, but it's damn hot outside so I am waiting until later this evening.

I called a repairman the first few times this happened but all they ever did was clean it.
posted by Ostara at 1:26 PM on July 18, 2006

Couple things it could be, people have you pretty well covered so far. Could be a blown fan motor, clogged fins, dirty filter, low refrigerant, all kinds of things.

Since the two options in your question are ignore it or call the repairman, I say call the repairman.
posted by empyrean at 1:28 PM on July 18, 2006

Just a follow on, normally when the AC cycles off any frozen water on the coils quickly melts away. However, when it runs at or near capacity and never cycles off it never gets a chance to melt. It is hell to turn the AC off for long enough to melt the ice, but it will help tremendously in the end if that is indeed the problem.
posted by caddis at 1:29 PM on July 18, 2006

You might also try taking the water hose and spraying off the side vents of the outdoor part of the unit. Often they are clogged with dirt and lint. The fact that the house does get cooler at night leads me to believe that the AC is not broken, but simply isn't large enough for your house to handle the hot weather. How many tons is your AC? How big is your house?
posted by mattbucher at 1:32 PM on July 18, 2006

foxinthesnow, are you serious about the freon theft ? I've never heard about that before, although I could be ignorant on the topic. Freon is not your usual "get high" gas like Nitrous Oxide-- I'm not sure that you can get high on Freon. This page says that Freon is exhaled easily and doesn't accumulate in the body.

Wouldn't it also be pretty non-trivial to find the coolant canister on an A/C, open it, and drain freon (and into what kind of container) ?

Also, without a coolant, an airconditioner really isn't an air conditioner-- its a fan. Most modern A/C won't start without proper coolant pressure anyway-- I had the problem in my car when there was a slow coolant leak.
posted by GreenTentacle at 1:57 PM on July 18, 2006

I really feel for you. I live in an apartment, but we experienced this problem every summer since we moved in. The maintenance crew did a number of things including checking and adding more freon (sometimes helped), changing the filter (always helped a bit), and telling us it was freezing up on itself and to not run the AC for an hour or so (never worked). Still, no matter what they did, our apartment was never as cool as we wanted it and when the temperature rose above 75 degrees outside, the temperature inside was between 75-80.

Finally with an early heat wave that hit this summer, the maintenance did all three things above and when that didn't work, they cleaned the coils on the outside unit and replaced the thermostat. I have no idea why it took them so long (nearly four years) to troubleshoot and resolve the problem, but I believe our issue was that the outside unit was clogged. (I am not sure if the new thermostat makes any difference though.)
posted by lynda at 2:08 PM on July 18, 2006


I am quite serious. It is super weird, but real. Just do a google search on "freon theft" or "freon huffing." You'll find quite a few articles like this one.
posted by foxinthesnow at 2:14 PM on July 18, 2006

I'll recap what I said in a previous AskMe question. Your A/C may be operating normally. There are a lot a variables here including the size of your unit, the amount of insulation in your home, windows and sun exposure, etc. A properly sized air conditioner will cool 18-22 degrees below ambient temperature. An HVAC tech will tell you that. Too large, and it will cool quickly but cycle too much to remove the humidity. Also, If your A coil is freezing up, either your unit is too large or your air flow is restricted.
posted by AstroGuy at 2:18 PM on July 18, 2006

What temperature is the air coming out of the vent?

If it's not cold, but instead "coolish" then you've likely got a problem with the unit itself (see above).

If it's cold, but the house never gets cold, then you've got a problem with the house (Poor insulation, a leak somewhere, or a unit that's too small for the house).
posted by madajb at 4:17 PM on July 18, 2006

It's 105 out right now and 80 inside here, which is about as good as my old house and old A/C ever manage, and there's nice cold air coming out of the vents. I'm in a rent house, so my options are limited. But I've got friends in new houses with A/C units for each floor who aren't getting below 75 themselves. Our 5 units at work are all struggling, with most zones around 78. My server room unit froze up this afternoon, which is lots of fun.

We have a window unit in the bedroom, and I just bought another one to put in the much smaller spare room so we can sleep in there through August.

Do make sure everything is clean outside. It's important that you gently wash out the little metal fins around the fan - don't use a pressure sprayer. I've now been told this by three HVAC guys so I'm taking it as vital for reasons I only partially understand. Cover your windows well, and get some fans. I've decided that the tall tower fans just don't hold a candle to the small Vornado-type fans, but that may be personal preference. I can tell that the hot air is just lurking near the ceiling, and the fans seems to be helping everything circulate and cool off more.
posted by Lyn Never at 5:12 PM on July 18, 2006

Definitely check for dirty fins and freeze up, but also get a thermometer and actually measure the outlet air. I think for a central system, you should expect it 50s to low 60s.
posted by baylink at 6:05 PM on July 18, 2006

Time to call the AC repairman. If you're lucky, he will just recharge the system and you'll be good for the rest of the season. But it will probably need to be replaced sooner rather than later.
posted by Doohickie at 6:15 PM on July 18, 2006

@Lyn: yeah; power companies will tell you that if you complement your A/C with ceiling fans, you will save *much* more money in A/C power than you spend in fan power; my experience is they're even more correct than they admit (they like to say that fans cool people, not rooms; my experience is that that's too restrictive...)
posted by baylink at 6:21 PM on July 18, 2006

I've been told it won't be 20 degrees below what's outside. New a/c and getting 78 degrees here, 105 outside. I'm sweating just sitting here, I can't imagine people without air.
posted by geoff. at 6:45 PM on July 18, 2006

I know that Freon isn't psychoactive. You know that Freon isn't psychoactive. But do teenage Freon thieves know that Freon isn't psychoactive?

Try drying out a bunch of banana peels and leaving them on the outdoor unit in a little box, with a sign on them saying "Smoking banana peels gets you higher than huffing Freon".
posted by flabdablet at 10:54 PM on July 18, 2006

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