Temperature drop in itself can not be used to determine if a system is running at capacity.
High indoor humidity can reduce the temp drop; wetbulb return/supply temperatures and airflow measurements are required to calculate system capacity.
The blower speed might be too high.
If you meant superheat, 19 might be a little high at 83F if it's dry; I can't tell without the wetbulb return air temp. The other numbers look okay.
Iv never heard of this but.
= 19 degree superchoat.
Edit: I assumed that the metering device is fixed; if it's a TXV you could have a major problem.
That will make a huge difference.
Also we are having an insulation company blow R30 this thursday.
For the record, running continuously for several hours is normal during hot weather.
The A/C runs all day during the day and will only keep the tempature till about 11am then it goes up in the afternoon. Then finally at 1am in the morning it will turn off when it goes to 76degrees and operate normally.
General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"