You can also check the air temperature away from the heat pump. Then compare the air temperature over the discharge air, moving it around to the coolest discharge air. You should get 9 - 12 degrees difference in the air temps.
Water temperature split if tested at the skimmer and the closest return line should be about 3-5 degrees. If you do not have this, you have problems with the unit. How old is your system? You many have warranty coverage on it still.
Are there any red lights on the control panel?