why doesn't my central AC cool my house lower than 72..Has been cleaned and is 3 yrs old. 6 rm house in MA.

Question

the guy who installed it says that is good for central air..But I want it cooler and all rooms aren't cooling equal...Can someone help me..I hate the heat

Answer 1

Check the air temperature at the filter and the air temp at one of the vents. You should get a 16-20 degree temp difference. If you do the unit is doing all it can do. Walter is wrong.
A house AC is not designed to maintain a 20 degree diff from the outside temp. This is also wrong.

Basic Example
In the area I live, load calculations are done based on a 97 1/2 degree day. Then the appropriate sized unit is installed.

If the house requires, lets say a 36,000 btu unit then on a 97 1/2 degree day, the heat entering you house will be 36,000 btu. So at that temp, the unit can only maintaine the temperature and will not be able to lower the temp. On cooler days the heat gain in your house will be less than 36,000 btu and the unit should be able to cool. As the years pass and the insulation settles and windows let in a little more air..etc then the unit will not keep up as well.

So it is very possible with these very hot days, that is what is happening.

As for the uneven cooling, this is very common in a house. Because from what i've seen, the duct installers just make the runs to the rooms, they don't check to see if the room is getting the correct amount of air. As menitoned you can get even cooling but the duct has to be installed properly and then adjusted using dampers. On most houses this is never done. On many, they do not even install the dampers.

There are many other items to consider with your problem but I hope you have enough information on what may be happening.

Answer 2

There are two seperate issues here, air balance and cooling capacity. Let's take air balance first:

After reading some of the above answers, I wonder whether I have stepped into the Twilight Zone. After 10 years of duct design, installation, modification, remediation, cleaning and trouble-shooting, I can assure you that air can and should be distributed evenly throughout the home. You have a poor duct design.

Cooling capacity may be another issue. If your interior temperature is twenty degrees lower that your exterior, your system would be considered to be operating within acceptable parameters. If it is 92 degrees outside, 72 degrees inside is great. If, however, it is 80 degrees outside, 72 degrees is not so good. It may be that you simply want more b.t.u.'s of cooling than the contractor allowed for. The question is, is the system sized properly for your home? The inside/outside temp. differential will help determine this. Ulimately, however, the only way to determine if the equipment is sized properly for your home is to have heat load calculations performed and checked against the b.t.u.'s of cooling provided by your equipment.

Answer 3

It's simple science miss.

I have a 2-story house that does not cool well in summer because.......heat rises. I'd have to have a central AC unit the size of a jet engine to force cool enough air to the upper levels for long enough to make it feel as cool as the lower levels.

It's no mystery, it's just how hot and cold air works. Ceiling fans help, craftily designed duct systems helps, but most of the time standard AC systems are not designed this way. Some rooms get more sun than others. The amount of heat one room gets versus another is dependent on the lay of the house to the sun and the landscape.

Unless you want to put fans in all your rooms to thoroughly circulate the air you'll have to settle for differences in temperature in the rooms in your home.

Answer 4

First - not all rooms will cool equally. Some are at the end of the vent - those will be slightly warmer. Fans placed at the vent will help with circulation.
Second - Is your thermostat old? Or in the coolest part of the house? Both could affect the air output.
Third - Do you have interrupt-able electricity on your AC? Some power companies offer a separate meter/account for AC - this way they can interrupt the power for short periods when the demand is high. They do this to lessen the pull on the power grid. They usually offer a discount or rebate if you have this. If you have this - during peak heat or peak power times - you will never get it to the temperature set.

Answer 5

The most you can get out of your A/C unit is 16/20 degrees cooler then the outside temperature. Example: if the temperature outside is 95 degrees than the most you can get blowing out of your registers in your home is 79/75 degrees. As for not cooling equally, you need to balance your system by adjusting your dampers. In the smaller rooms you need to close off more and the larger ones you need to open them more.
Good Luck

Answer 6

you'd need more BTUs (i.e., a larger air conditioner) to get it any colder than 72.

(As a side note, if you're looking at cooling it down that far, I hope you're not environmentally conscious...)

rooms ordinarily don't cool evenly. some get more sun and are warmer, or are at the end of ventilation pipes and so get less cold air flow. that's just the nature of the thing.

Answer 7

The compressor may not have the right amount of freon in it. It may have a slow leak. Have a guy come out and check the level.

Answer 8

You will need to reduce the heat load by sealing up cracks with caulking adding insulation especially to the attic. get thermopane windows

Answer 9

needs refrigerant recharged used to be freon now r12 in autos not shure about type of unit call ac service to recharge system may also have pressure leak needs new o rings ....they replace them when they recharge system