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.
How It Is Done. You can measure your pulse rate anywhere an artery comes close to the skin, such as in your wrist or neck, temple area, groin, behind the knee, or top of your foot. You can easily check your pulse on the inside of your wrist, below your thumb. 1  Gently place 2 fingers of your other hand on this artery.2  Do not use your thumb because it has its own pulse that you may feel. 3  Count the beats for 30 seconds; then double the result to get the number of beats per minute.our pulse is the rate at which your heart beats. Your pulse is usually called your heart rate, which is the number of times your heart beats each minute (bpm).