The EM-2000-OT is a fully operational system to demonstrate the physics in air conditioning system. It uses an orifice tube to control the flow of the refrigerants. All major components in the system can be clearly visualized, allowing students to carefully observe the flow of refrigerant and its change of state which involves physical change of state between vapor/liquid. The EM-2000-OT is also equipped with high and low side pressure gauges to offer real world diagnostics capabilities which allows instructors to introduce system restrictions or blockages for learning purposes