The RD Holder HVAC Pro App is to help a AC technician service an Air Conditioning system. Troubleshooting of an air conditioning system is a step by step procedure. I have found that a 4 step procedure is the best way to see how well a system is operating. The 4 steps are: 1. Volts and Amps, 2. Evaporator Superheat, 3. Condensing Subcooling and 4. Temperature difference of coils. Not one of these method alone can be used by itself to charge or troubleshoot an air conditioning system rather they must be used together to ensure efficiency and capacity.
Not only is voltage very critical but the amp can tell us how hard a compressor is working and is a good indication of a charge
Evaporator superheat is a calculation of the amount of liquid refrigerant going into the evaporator and the heat load of an air conditioner evaporator.
Subcooling is the amount of liquid held back in the condenser. This allows the liquid to give up more heat, below saturated pressure- temperature.
Temperature difference of an evaporator coil will vary with the total heat of the air entering the evaporator and the load on the condenser. This temperature will vary from 10º F to 30º F depending on total heat of the air entering the evaporator.
When you download HVACPro you will get both the phone version and the pad version. The first 5 diagrams are the phone version the last 4 are for the pad version.