As pressure on a gas decreases, the gas expands and cools; increasing pressure makes the temperature rise. You could also express these phase changes as evaporation and condensation, which is how evaporator coils and condenser coils get their names. Refrigerants, including Freon and Puron, may never need recharging throughout the life of your AC.
1 Make sure that the start of the ruler is directly below the center of one eyeâs pupil. 2  Hold the ruler (keeping it steady and parallel to the floor); mark the location on the ruler of the other eyeâs pupil. 3  Measure the distance in millimeters between the two marks. 4  That distance will be your PD.
Measuring the carotid pulse. Place the tips of the index and second fingers of one hand on the side of the neck just beside the windpipe. Measuring your resting heart rate. Your pulse fluctuates during the day due to activity, stress, caf-feine, medications, and other factors that might influ-ence your heart rate.