Low suction pressure, low head pressure, high superheat and low sub-cool
Undercharged
High suction pressure, high head pressure, low superheat, and high sub-cool
Overcharged
High suction pressure, low head pressure, low/normal superheat, low/normal sub-cool
Bad compressor valves
Low suction pressure, low head pressure, high superheat and high sub-cool
Liquid line restriction
Low suction pressure, low head pressure, high/normal superheat and high sub-cool
TXV underfeed
Low suction pressure, low head pressure, low superheat and low/normal sub-cool
Light evaporator load
High suction pressure, high head pressure, high superheat and low/normal sub-cool
High evaporator load
High suction pressure, high head pressure, low/normal superheat, low sub-cool
TXV overfeed
High suction pressure, high head pressure, low superheat and low sub-cool
Lack of condenser air
High suction pressure, high head pressure, low superheat and low/normal sub-cool
Air and non condensables in system