I set my thermostat at 72 but it never reaches 79, it constantly runs till late at night. I live in a mobile home and have a outside condensing unit, I was told it might be the thermostat, I appreciate any help.
Mark1368, Heatseeker and theduke are correct in asking these questions as they are trying to determine the cause of your problem. Not sure if you know but the delta T is the temperature difference between the supply and return air. The air temperature going in and out of your AC unit. The best way to check this is to have a thermometer with a probe to stick into the air stream. Not everyone has one of these. You can also use a small house thermometer and measure the temperature at the return vent and the supply vent not the best but will work in a pinch.