AC not starting.

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Old 03-19-14, 01:53 PM
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AC not starting.

Hi all,

My AC started acting up, I usually have it at about 68-70F, lately it would take a long time to restart, the house would be considerably warmer (75-77F) before it would "kick in" again, and on the last few days it just doesn't kick in at all, after I turn it on (auto) it cools down the house to the desired setting and "shuts off", but won't restart no matter what temp the house reaches, and I can lower the setting to 50's-40'sF but it just does not restart.
If I turn the switch to OFF, and let it sit for a period of time, I could come back and turn it on again (auto) and it would kick in, except for yesterday, it just won't start, not matter how long I wait, I let it sit all night and tried this AM but nothing,or what setting I use (on/auto/heat/vent) and no matter what temp.

This is an apartment in Florida, unit is in the ceiling and the main piece is on the roof (9 store building), the controls are pretty old (from the 50's-60's), but the unit itself is new I believe, (2011-2012)

Anyone have any idea on what is possibly happening?

Thanks a lot, and sorry for not having the proper terminology
Pavao.
 
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Old 03-19-14, 03:43 PM
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Is this a low voltage thermostat or a high voltage thermostat?

Is this a geothermal unit, a chill water unit or do you have refrigerant lines trying to pump refrigerant 9 floors? (The last option is unlikely)

The make and model number of the stat and indoor unit would be of great assistance.

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Old 03-19-14, 05:20 PM
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I have no idea Houston204, sorry, I actually don't even know what those mean

I just got home and started to play with the thermostat, pulled the cover off, and just played with the switches a bit, nothing happened. In the process of putting it back together I accidentally dropped the cover and all the pieces came apart, I did put it back together and reattached it to the thermostat, played with the switches a little more and still nothing.

Then, I looked at the part below, which is a honeywell (?) humidity control, I'm not sure exactly what I did, but touching it got the AC to start, I didn't play with it much, but when I tried to pull the cover off on it, I gave 2 gentle pulls on it and all of a sudden the AC started.

While I was writing this, the AC stopped, like when it reaches the desired temp, I went to look at the thermostat and played with the switches again, nothing again. Then I focused my attention once again to the humidity controller (?), gave a few gentle pulls on it again and nothing happened, I then moved the dial and it kick started the AC, move one way it stops, move the other way it starts, multiple times, like it was an on/off switch, I'm already starting to feel stupid.

But anyways, can someone explain what is going on?
Let me clarify a few things...
Apparently I'm not 100% sure on how the "controllers" of an AC works, to be honest, I have never touched the humidity control, whatever it was set on, it stayed on.
I also never learned what the "on/vent" function on a AC is for, as far as I know, if I set it to on/vent, the unit will continue to blow air non stop, but I have no control over the temperature, it just blows room temperature air continuously, what is that function for?

Thanks a lot
Pavao

The controls IMG_0979_zps918f917f.jpg Photo by MPavao | Photobucket
 
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Old 03-19-14, 07:43 PM
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Pictures are worth a thousand words.

You have a low voltage thermostat and a humidistat. Either one should start the A/C running. This setup is fairly common in high humidity areas. If you were to leave the premises, like going on a vacation, you'd turn off the thermostat and set the humidistat to whatever percentage of humidity you would want the A/C to come on which would start cooling and dehumidifying.

Your humidistat is currently set to 60%. That means when the humidity exceeds that setting the A/C will come on. When the humidity goes below that point the A/C will shutoff.

If you had parts of your premises that run hot and some run colder...... you can put the system to FAN ON and the blower will run and help equalize the room temperatures. In some cases this can actually save energy by allowing the compressor to run less.

That looks to be a fairly old thermostat and may be your problem. Houston will stop by and add his comments too.
 
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Old 03-19-14, 08:45 PM
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Checking the stat is a good place to start...

After removing the thermostat cover you should see 3 screws above the locations that I have highlighted blue. You have a vertical model but it appears to use the same subbase turned on its side.

If you are lucky the problem may only be dust between the small ball bearings and the contacts that they touch as you move the switches from Cool to Off and Heat.

I sometimes just blow out the dust and clean with a small dry paint brush to correct this.

If this fails to correct the problem, you can temporarily bypass the stat to prove operation of the equipment.

Take a picture of your wiring before removing any wires...

RC and Rh (sometimes just R) is 24 volt power. G is fan. Y is cooling and W is heat.

You can touch the R wire to the G wire to bypass the stat and run the fan.
If you also add the Y wire the fan and cooling should run.
 
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Old 03-20-14, 06:20 AM
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Tyvm guys, I think there isn't anything wrong with the system after all. Looks like was just the setting on the humidistat set to a value too great and because of that it would never allow the AC to turn on.
I did remember messing with it last week for some reason, I think I even removed the knob, and I guess when I placed it back it must've been when I screwed up the setting.

I still need help with 2 things though...
1) First is simply help understanding how to properly set the humidistat, what value is ideal, and how do I find out what is ideal where I live? Looks like the humidistat overrules the thermostat, correct?

2) When I accidentally dropped the thermostat front cover, and all pieces went flying everywhere, the little piece that measures temp, it's a little needle which is all coiled up and attached to a "pin" that simply plugs into the cover, I putted it all back together, but I believe it must be reset, it's measuring about 10F lower.

Thanks a lot guys, tremendous help here, before I found this site I had posted these questions to the HVAC-Talk forum, no one is willing to help there.

Pavao
 
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Old 03-20-14, 09:36 AM
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There is no "set" humidity level to set the control too. It may be a trial and error setup based on feel. You could also pickup a humidity gauge, watch it for several day and then select a humidity level based on that.

The spring on the thermometer is probably bent. That won't affect the control temperature. You can just put a thermometer on the wall next to it.
 
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Old 04-29-14, 08:29 AM
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Hello guys,

I'm back to this thread again...
As I have explained in an earlier post, I have figured out the problem with turning on/off the unit, however, it is not cooling as it should, air is slightly cool but not as near cold as it used to be, in fact, it can't even cool down the house enough to the desired temperature, the ac will just stay on non stop through out the night, it lowers the house temperature, but not enough.

Putting my hand over the vents I can feel air is just simply not cool enough, kinda like in a car when it's low/out of freon, but somehow I'm skeptical that the problem is actually freon, reason for that is the earlier problem I posted, I can't see the relation, I'm more inclined to think the problem is with the controls, but then again, what do I know?

Edit: Forgot to add that another reason I don't think its a freon problem, is that it never freezes, the unit runs non stop, but never freezes, which would be a clear sign of low freon I believe.

Help please
 

Last edited by Pavao; 04-29-14 at 08:35 AM. Reason: Forgot about freezing
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Old 04-29-14, 08:54 AM
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The freon level might be so low, it's past the point of frosting. Clean filter?
 
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Old 04-29-14, 08:57 AM
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To find out if the AC is working or not, simply go to the condenser and check to see if the compressor is running. If it is not running, then you have control problem, if it is, then you have AC problem.
 
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Old 04-29-14, 09:10 AM
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How can I test to see if it's indeed a freon related issue? And if so, is that something I will be able recharge myself?

Filter is dirty, I don't know how dirty it needs to be to affect this, here's a pic of it...
MPavao's Recent Uploads | Photobucket

Also a pic of the unit and where the filter goes.

I'm running the unit right now like that, without the filter to see if it improve any on the cooling.
 
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Old 04-29-14, 09:16 AM
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clocert, I really appreciate the help, but you just spoke greek to me lol, I have no idea what a condenser is, let alone find where it is located, same goes for the compressor.

Aside from the air just not being cool, everything else sounds like its working just like it ever did.
 
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Old 04-29-14, 09:20 AM
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Your on the right track, run it for a while without filter. Be sure to get a new filter, that one is pretty bad. Charging the unit is not a DIY, you will need a pro for that.

Your condenser is on the roof.
 
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Old 04-29-14, 09:26 AM
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Ok, so the condenser is the other half of unit, the one on the roof?
I was/am heading there right now, what should I look for, anything in specific to verify its working properly?
 
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Old 04-29-14, 09:35 AM
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When you get up there you'll find lots of cond, do you know which one is your's?
 
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Old 04-29-14, 09:40 AM
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Alright, the roof unit is working as far as I can tell, working properly idk, but it is on.

The metal pipeline that comes from it to the house, I touched it, and it is cool and has condensation. Comparing it to a small sample of other units around (my neighbors), it feels same as many others, but there are some which feels considerably colder.
 
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Old 04-29-14, 09:52 AM
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Oh ok I thought this was an apartment. Condensation is good, but all that tells you is the pipe is cooler that the outside temp. Check the pipe that is going in to your air handler. See if it feels cold.
 
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Old 04-29-14, 10:04 AM
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Yes, it is an apartment, but I was able to figure out which one is my unit.

Hmm, need help on that lol, which/what/where is the air handler?
 
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Old 04-29-14, 10:21 AM
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No prob, thats the unit in your apartment.
 
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Old 04-29-14, 10:48 AM
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Hmm, so the half on the roof is called a condenser, and the other half inside the ap is called the air handler. thanx, it will keep getting easier for me to pass information to you guys.

It looks like that same pipe, if I have identify it correctly, when it gets inside the house, it is insulated, it is wrapped in foam, kinda like a swimming pool noodle, and it is hard to reach too, I couldn't touch it.

Anyways, I had called a guy, he was just around the corner and just got here, I'll update the thread.
 
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Old 04-29-14, 01:55 PM
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Update

OK, guy came in and measured the freon on the condenser, it was about 55, so he added some, bringing it to 75. That brought the pipe I mentioned earlier to be considerably colder.

Before that, he used his laser thermometer to measure temp at the vent, then on the ceiling, after the addition of freon, the temp on the vent dropped according to his laser thermometer, I must say though, using my hand as a measuring device, I don't see any difference, I kept constantly putting my hand over it to feel how cold the air is over the last couple days and did it a few times just prior his arrival and his addition of freon, after the freon it still feels the same to me, also I clearly remember waking up some mornings few months ago (when my uncle is here he sometimes puts it at 65 or less lol) and feeling that vent, and it seemed like the coldest air you could possibly feel, this vent is on the kitchen, it's the closest to the unit and low too, right above my head when i go to the kitchen, so, you can't not notice that freezing air on you.

Another thing bugging me, is the fact the unit never disarms (turn off when desire temp is reached), the house is much cooler inside than the temp outside right now, but still, it has been running for at least 2 and 1/2 hours since he added the freon, not to mention it has been running since yesterday, and it does not cool down enough to the point of the unit disarming, I have it set now to about 65F, and though the house is much cooler than the 88F outside, it is still not cold enough inside, I'm a person that gets cold easy, and in the past I would certainly be cold by now, cold to the point of going over to the thermostat and adjusting it to a higher value.

My understanding, and in clarifying this with the guy, what I know is that no matter what setting of temp I put on the thermostat, the intensity of the air being blown and it's temperature will always be the same, weather I set it to 70F or 40F, at the vent it will always be same, so, I simply cannot understand why either one of 2 things aren't happening,
1) Why hasn't the house reached a temp where I feel cold?
2) Why isn't the unit disarming?

Question 2 is an obvious answer when we look at question 1, but I just put it out there to eliminate the possibility of the thermostat being screwed up, lets say I think I'm setting it to 65F, but since it's faulty, it is actually set for 72F, which would make the unit disarm even sooner, but like I said, it does not disarm, and I'm not freezing.

HELP PLEASE
 
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Old 04-29-14, 02:10 PM
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What you set the thermostat to is just a setting. Don't you have an actually thermometer to tell you what the air temperature is in the room ? Holding your hand in front of the register doesn't give you an exact temperature reading. Use a thermometer.

The unit wont stop until the air reaches a certain temperature OR in your case a certain humidity.

Now....why the unit won't get cold enough should have been handled by the technician you just had there. You also need to remember that the lowest temperature inside that the air conditioner can cool to is dependent on the outside air temperature.
 
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Old 04-29-14, 02:39 PM
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Pavao, It doesn't matter how low you set the temp, the unit can only produce to its capacity at a certain temp depending on outside temp. The best way to tell if the system is running properly is to measure temp at return air (where your filter is) and supply register closest to the unit ( kitchen?). The difference between these temps should be 15* to 20*. It will probably take 5 to 6 hours to cool down, at88* and high humidity.
 
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Old 04-29-14, 02:41 PM
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PJmax, I understand what you're saying, but here's 2 facts.

1) I'm not cold, don't need a thermometer to tell me that.
The comment about feeling the air with my hand, though it's not accurate reading, it is certainly possible to tell from from cold/hot, or freezing/just cool, specially when you have a point of comparison. You don't actually use a thermometer to measure how cold your preferred beverage is, do you? Just grab it and we are able to tell.

2) The unit is not disarming.
For this, you have to take in consideration that it is not frozen (air is blowing from vents non stop), humidistat is set very low (40%) and all windows/doors are closed.

So, the 2 don't add up. Either the unit should freeze up and stop blowing air, house reach temp to match setting of thermostat and disarm unit or I freeze to death, no?

Neither of the 3 is happening.
 
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Old 04-29-14, 02:47 PM
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Ok skaggsje, that only adds a 4th possibility then, which is my memory being faulty, lol.

I live here for about 2 years, I don't remember it ever being like this.
 
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Old 04-29-14, 02:49 PM
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The humidistat is set to 40%...... that means if the humidity is over 40% the A/C will run.
 
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Old 04-29-14, 02:58 PM
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Precisely PJmax, I intentionally set to that value, to avoid the unit from disarming because of the humidistat, now, why isn't the house freezing then?

Understand my question now?
 
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Old 04-29-14, 03:05 PM
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I know what you are saying, but have you been there when the unit has broken down before? It will take a few hours, then it will freeze you out, lol.
 
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Old 04-29-14, 03:08 PM
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What is the current outside temperature ?
 
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Old 04-29-14, 03:16 PM
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Alright skaggsje, lets give time then, sun will be setting soon too, so, should be cooler out.

Btw, if I set humidistat for a very low setting, lets say actually 0%, will the unit disarm when it reaches the set temperature, or will it keep on going past the temp set because of the humidistat?
 
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Old 04-29-14, 03:18 PM
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The unit should not turn off from the humidistat if the house temperature is above the thermostat setting. If that's happening, you still have a control issue.

Turn the humidistat up to 70 or more, turn the t-stat down to 60, does the unit turn off or stay on?
 
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Old 04-29-14, 03:19 PM
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PJmax, it's about 84F now outside.
 
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Old 04-29-14, 03:23 PM
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Yea it will keep running forever. I would set it at 45%. To be honest with you, I would get rid of the humidistat, in your climate the A/C will run enough to keep the humidity down.
 
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Old 04-29-14, 03:27 PM
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tomf63, the unit turns off when I dial the humidistat up to about 55, with the t-stat at 60F.

By control issue, you mean the humidistat/thermostat, replacing those could solve the issue?

The guy recommended me changing them, not because it was faulty (not sure he knows weather it is or it isn't faulty though) but because its so old, he was recommending a more modern, digital one, about $120 to replace

Can that be a DIY job?
 
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Old 04-29-14, 07:59 PM
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Replacing the h'stat and t'stat will make the process more automatic but won't make the system cool any better. If you are always at this location - don't use the humidistat...... just use the thermostat. Humidistats were mostly installed for people who were away from their home a lot and didn't want the humidity to get too high.
 
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Old 04-30-14, 05:07 AM
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tomf63, the unit turns off when I dial the humidistat up to about 55, with the t-stat at 60F.
You still have a control issue. Sounds like the t-stat is shot. Right now the unit is only being controlled by the humidistat.
 
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Old 04-30-14, 05:09 AM
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Ok, A/C ran all night and the unit never disarmed once, I was awake until about midnight, fell asleep on the couch and woke up at about 4 am, which is a time as cool as we can get on any given day right? If there is a good time to test this, I'd say 4 in the morning is as good as we can get, I was awake for about an hour and it never disarmed once.

I have a suspicion that the unit is blowing air at intermittent temperatures, cold for a bit, then no so cold, then cold again, kinda like instead of disarming, it continues to run, but not blowing cold air. I think the house temp rovers around the 70-73F, it cools down some because the unit does blow some cold air, but will never get below that because it doesn't continuously blow the same cold air, does that make sense? Is this a known behavior, sign of something wrong?
 
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Old 04-30-14, 05:15 AM
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tomf63, if I adjust the t-stat to higher value, it will shut off the unit, would that be normal, even though it's shot?
 
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Old 04-30-14, 06:03 AM
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What is this dial here in the middle? Could it have something to do with it? I may have screwed with it a little, I can't remember.

Also, there's that little piece of sponge there, seems like it was wedged there improvised?

IMG_1162_zpsadcd6c64.jpg Photo by MPavao | Photobucket

IMG_1163_zps285b9e4d.jpg Photo by MPavao | Photobucket
 
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Old 04-30-14, 09:22 AM
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Hi guys, sorry for bombarding you with so many questions, I'm just frustrated with it, specially after the "technician" came in, I'm doubting his knowledge and abilities at this point.

Anyways, here's a theory

A wild assumption on how A/Cs work;

(C)----> (F)----> (V)

C= cold air
F= fan
V= vents

As my highly sophisticated diagram shows, cold air (C) is blown into a powerful fan (F) which then is forcing all the air through the conduits and spreading that air through out the house by the vents (V).
If (C) is blocked, all I would get is room temperature at the vents.
If (C) is partially blocked, all I would get is partially cold air, or air that isn't as cold as it should be.

This would explain why the house cools down some, but not as nearly as it should or did in the past, no?

What do you guys think?
 
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