Outside/Inside temperature differences

[kawkvulcan500]

Can anyone tell me if there is a general rule for units when the outside temp is X degrees, the unit should be able to cool down to Z degrees?
I think my unit may be dying... the outside temp is about 88F and the unit is barely keeping the house down to 75F (thermo is at 72, so I like it cool.)

[Dad]

Some may differ but something like 18 to 22* difference.

But there a lot of variables involved

[sadlier]

That is the main purpose in calculating heat gain in the heat load calculations - to determine what size of unit is required to maintain a given temperature differential between indoors and outdoors. Some areas are OK with 10° and others prefer over 25°. It depends on the area you live in.

[kawkvulcan500]

I live in South Louisiana. Gets pretty hot down here during the summer.
The unit I have is original to the house which is about 20 years old. I know the efficiency must have dropped off some, but other than this temp difference issue, she is working OK.

[sadlier]

What's your city or what is the closest large city?

[kawkvulcan500]

NewOrleans

[sadlier]

The ACCA recommended value is 75° indoor @ 92° outdoor = 17° TD.

[ct2]

Have you changed the filter? how often have you been changing it and how dirty are they when you change them

[kawkvulcan500]

I have an electrostatic filter that I clean usually once a month. Sometimes its dirty and sometimes just a little.
The filter is a little old... time for a new one maybe?