These three HVAC quick reference polystyrene cards are double sided and designed to be used with Air Conditioners and Heat Pumps to measure the refrigerant level in a unit, charge refrigerant, troubleshoot refrigerant based problems, and measure heat transfer to determine if there is a problem.
 
Find the Target Subcooling to measure the refrigerant level of systems with a TXV metering device
Use Subcooling to determine if a system is undercharged, correctly charged, or overcharged
Find the Target Superheat to measure the refrigerant level of systems with a fixed orifice metering device
Use Total Superheat to determine if a system is undercharged, correctly charged, or overcharged
Use Delta T to determine if the system is exchanging heat properly
Use the P/T Chart to find the Saturated Temp of 5 common refrigerants
Use the Guide to determine how to find the Bubble and Dew Saturated Temps of Blend Refrigerants
Use the Refrigerant Weight Chart to calculate the amount of refrigerant needed per foot of tubing
Use the Guide to weigh in the full or partial refrigerant charge into an empty vacuumed unit