Pyongsan's coaxial tube bending and assembly uses a double-layered tube to carry both suction and liquid lines within the internal heat exchange system. Previously, suction and liquid lines for the internal heat exchanger were manufactured separately and assembled afterward. Coaxial tubing produces one shared tube composed of an inner and outer layer. The inner layer carries low-pressure suction gas, while the outer layer carries high-pressure liquid coolant. Benefits include improved quality control, since only one coupler is used for both suction and liquid lines, as well as reduced material and fabrication costs and enhanced forming performance through the use of multiforming. A robot bender is used to increase production capacity, and HVAC performance is improved for a longer period without increased refrigerant use.