AC issues.

We built our house back in 2008. We went a Carrier unit because it was supposed to be the best. Within 2 years, the until quit cooling completely in the middle of summer in close to 100 degree weather. The first time the HVAC company fixed it. It was a cracked coil in the handler that made it lose all Freon. 2 years ago, it does it again, this time we are out $1100 because it was out of warranty. We have a bonus room that my 2 nieces have moved into that is insulated with it's on thermostat. The AC is set to 70 but it will not cool the room down past 82 the past few days. At night it will catch up, but not until a few hours after dark. Now the main floor is not cooling right. Thermostat is set to 69 and it the temp is now 72 in the house. I'm just tired of the AC not working like it's supposed to, but I can't afford to replace the unit now. What are my other options?

Do you have good circulation in the attic?

My first house would never get below 80 in the summer days, after years of hating that, I finally installed an attic fan (not a whole house) an attic fan cools the attic, it helps a lot, especially if your duct work is in the attic
Also, make sure you are changing your filters about once a month, especially in the summer.

X2 on the attic fans. We had issues with ac running a lot and the unit was fine. Ac guy said our attic was too hot (Something like 140*) put in two belt drive attic fans that come on when the temp gets to 110* in the attic. Helps the ac a bunch. Bought them for about 100 each if i recall correctly from HD.

We have an upstairs we don't use very much. It never gets really "cool" in the middle of the day. We put a window unit in one room, and run it as needed, and it does very well. We don't even notice it on our power bill.

You can get portable units that don't even need a window, and they seem to work very well.

Attic fans are good, but for the nieces, a portable A/C might give them more relief.

Funny you should mention that, I have added a attic fan with thermostat last week. I don't feel like it is working like it should though. It moves a lot of air, but there is a lot of backflow. I think I am going to have to modify the gable by breaking a few plastic grates off, then add another fan on the other end in a push/pull configuration.

Look outside at your copper line that comes into your ac and see if it is frozen. If so, your low on freon again. I have a leak in my coils so rather than fix it, I have freon added every spring. But once you add freon, DO NOT turn your heat back on until winter. It works on a higher pressure which will cause you to loose your freon again. Your freon leak should be very small and should last all summer.... as long as we dont have a cool night and someone in the family turns the heat back on. Your attic ventalization should not be your issue in the main house, not this time of the year, unless you have dealth with this every year. My bonus room also has trouble keeping up. The lack of air space in a typical bonus room is a problem. Do you have vented soffit. If not it is like a radiator with stopped up lines. Hot air rises, but only if it is replaced with other air. If you have good soffit ventalization, then the heat rises causes a pull or vaccum to draw the outside air in through the soffit and up through the attic. It can actually have a radiator cooling effect of a few degrees on everything the air comes in contact with. But this is not the goal. The goal is to get the hot air out. If your soffit vents are working very well, moving lots of air, they will actually be dirty, like they are a course filter. On vinyl soffits, it is almost like a static cling. Air rather than water usually will clean them up. Sometimes the framing or insulation restricts the flow from the soffit to the ridge in a typical bonus room. Of course a bonus room does not have to be typical, but the name came from claiming attic space, finding bonus space, which usually means a clipped ceiling, the restricted area causing the problem.

How big is your attic? I have a medium pitch roof on about 2k sq feet. The largest one HD sold wasn't enough. Installed a second one And it has helped a bunch.

One other thing to think about...do you have ridge vents? When the roof was put on...were the vents covered up?

Really...if the attic is over 120*...your gonna have trouble with the ac keeping up. I'm curious what your attic temp is. That will help you decide what the problem is.

I work in a lot of attics. Often going in dated houses, raising ceilings, mostly turning them into trey ceilings of homes with 8 ft ceilings. Some are dangerous hot up there.... others were not so bad, for whatever reason. Over time, I have determined that those what I call whirly bird type that have no motor, they just spin as heat escapes, they do a good job of removing heat

If your inclined to watch over a power vent, to keep check on it, knowing that it will not last long, they do the best job...... but no ridge vent or gables vents. Your trying to pull through the soffits. If you have a power vent, it will pull from the least restricted so if you have ridge vent, your power vent will pull outside air in and that same air out. Never removing the bulk of your targeted hot air

lbzdually said:

Funny you should mention that, I have added a attic fan with thermostat last week. I don't feel like it is working like it should though. It moves a lot of air, but there is a lot of backflow. I think I am going to have to modify the gable by breaking a few plastic grates off, then add another fan on the other end in a push/pull configuration.

Click to expand...

The house I put my fan on was about 1500sqft, and the fan was rated to up to 1600sqft. Check out the rating on yours, if you are close to the limit a second one probably isn't a bad idea. Circulation is super important, if you don't have perforated soffits, than that could keep your fan from being efficient. I also remember reading that you should install you fan to blow with the wind direction. I know in Ga the wind swirls bad, but it generally blows east. If the wind is blowing towards the fan, it will reduce the efficiency.

My soffit is perforated, but it does looks dirty, like a lot of the blown in insulation has migrated to cover par of the soffit. I do have ridge vents also. The attic area is around 2500 ft and the fan I bought is rated at 2600. Last night, I got some talcum powder and squeezed it out and instead of it being sucked up and out of the gable, a lot of it blew back in. So my first step tonight after it has cooled down is to modify the plastic gable. I will check to see it the line is frozen. I just know this is not nearly as hot as it will get and this is only going to get worse as the summer goes on.

I want to get a thermometer up there just to see what temps exactly I'm dealing with. It's fine for me, but we are talking about teenage girls here and they are particular. The first night they were here they set the temp to 60 degrees. I went up there and it was freezing and they had 2 fans on them but had 2 comforters on. I suggested a small sheet or blanket and 70 degrees, but I'm trying to take into account they were used to this at home and it will just take time to adjust. I'm tempted to put in a split unit with it's own meter so they can set it to whatever they want, but they can see what setting the AC that low does to a power bill.

Is this bonus room on its own thermostat?

1gr8bldr said:

Look outside at your copper line that comes into your ac and see if it is frozen. If so, your low on freon again. I have a leak in my coils so rather than fix it, I have freon added every spring. But once you add freon, DO NOT turn your heat back on until winter. It works on a higher pressure which will cause you to loose your freon again. Your freon leak should be very small and should last all summer.... as long as we dont have a cool night and someone in the family turns the heat back on. Your attic ventalization should not be your issue in the main house, not this time of the year, unless you have dealth with this every year. My bonus room also has trouble keeping up. The lack of air space in a typical bonus room is a problem. Do you have vented soffit. If not it is like a radiator with stopped up lines. Hot air rises, but only if it is replaced with other air. If you have good soffit ventalization, then the heat rises causes a pull or vaccum to draw the outside air in through the soffit and up through the attic. It can actually have a radiator cooling effect of a few degrees on everything the air comes in contact with. But this is not the goal. The goal is to get the hot air out. If your soffit vents are working very well, moving lots of air, they will actually be dirty, like they are a course filter. On vinyl soffits, it is almost like a static cling. Air rather than water usually will clean them up. Sometimes the framing or insulation restricts the flow from the soffit to the ridge in a typical bonus room. Of course a bonus room does not have to be typical, but the name came from claiming attic space, finding bonus space, which usually means a clipped ceiling, the restricted area causing the problem.

Click to expand...

Just because a suction line freezes does NOT automatically mean it is low on refrigerant. Could be an air flow problem....If the line is frozen check your filter first. Being that you already had your coil replaced due to a crack...you should check to be sure that the line set (copper lines from condensing unit to evaporator) is properly supported in the attic. I have seen issues at the evaporator coil due to the lines being "limp" and not supported or tied with webbing or some other material. The weight of the line set and vibration causes the manifold in the evaporator to crack.

This part is totally FALSE. The unit does not operate at higher pressures in heating modes. The suction and discharge pressures will change, but only due to the reversing valve on a heat pump. Depending on where the leak is, discharge side or suction side will determine how quickly the unit leaks.

Does your bonus room have a return? Most do not and this is the most common problem with bonus rooms. The bonus room will cool somewhat with the door open to the room due to air being removed by returns in other parts of the home. When the door is shut and there is no return, the room "fills up" with air and the small amount of conditioned air from the air handler that is usually supplied to the room cannot enter as the room becomes "equalized".

If the bonus room has it's own thermostat, then I assume this is a zoned system. Make sure that the damper for the bonus room is operating properly.

1gr8bldr said:

Is this bonus room on its own thermostat?

Click to expand...

Yes it is. Cold air coming front the vents, but it just doesn't seem as cold as it should. I thought maybe it as because the lines run through the very hot attic, but downstairs is the same story.

Harlee said:

Just because a suction line freezes does NOT automatically mean it is low on refrigerant. Could be an air flow problem....If the line is frozen check your filter first. Being that you already had your coil replaced due to a crack...you should check to be sure that the line set (copper lines from condensing unit to evaporator) is properly supported in the attic. I have seen issues at the evaporator coil due to the lines being "limp" and not supported or tied with webbing or some other material. The weight of the line set and vibration causes the manifold in the evaporator to crack.

This part is totally FALSE. The unit does not operate at higher pressures in heating modes. The suction and discharge pressures will change, but only due to the reversing valve on a heat pump. Depending on where the leak is, discharge side or suction side will determine how quickly the unit leaks.

Does your bonus room have a return? Most do not and this is the most common problem with bonus rooms. The bonus room will cool somewhat with the door open to the room due to air being removed by returns in other parts of the home. When the door is shut and there is no return, the room "fills up" with air and the small amount of conditioned air from the air handler that is usually supplied to the room cannot enter as the room becomes "equalized".

If the bonus room has it's own thermostat, then I assume this is a zoned system. Make sure that the damper for the bonus room is operating properly.

Click to expand...

It does have a return. We also try to keep the door open because the HVAC guys said that because of the length on the run, keeping the door open may help.

lbzdually said:

Yes it is. Cold air coming front the vents, but it just doesn't seem as cold as it should. I thought maybe it as because the lines run through the very hot attic, but downstairs is the same story.

Click to expand...

If you can, take a temperature reading of the supply air and compare to the return air. There should be at least 10-15 degree difference at the supply and return vents. If you can get the temperatures at the return and supply plenums at the unit itself, you should be getting 18-20 degree difference. Make sure that the vents are sealed around the "boots" where the duct work (assuming flex duct here) and at the supply and return plenums. Air flowing through the duct or plenum can cause a venturi effect and draw hot air from the attic.

With the bonus room having its own thermostat your house may have a "zone" system. If the bonus room is calling for cool then more air is sent upstairs and the downstairs is cut back. Raise the thermostat in the bonus room and see if the downstairs starts getting cooler and more air is coming out of the downstairs vents. My son has a similar problem and we will probably put a window unit or one of those Mitsubishi units in his bonus room. His bonus room is just too large to cool down with the two small vents they installed.

cullyhog said:

With the bonus room having its own thermostat your house may have a "zone" system. If the bonus room is calling for cool then more air is sent upstairs and the downstairs is cut back. Raise the thermostat in the bonus room and see if the downstairs starts getting cooler and more air is coming out of the downstairs vents. My son has a similar problem and we will probably put a window unit or one of those Mitsubishi units in his bonus room. His bonus room is just too large to cool down with the two small vents they installed.

Click to expand...

I think this may be the issue. The AC has enough capacity to cool the downstairs, but once the bonus room AC has to kick in it is beyond what is can do.

Ac

Also, remove your return filter and stick your head into the duct and see if the coils are clean. IWe change the filter often but mine was about 25% stopped up this spring. Reduced air flow= longer running unit.