Heat exchange system for outdoor unit of air conditioner and air conditioner

A heat exchange system for an outdoor unit of an air conditioner, comprising:

• an outdoor unit heat exchange assembly comprising a coolant heat radiation module and fins;
• a first circulation pipeline comprising an output pipe, a connecting pipe and a return pipe, wherein the output pipe communicates with an air conditioner indoor unit and the coolant heat radiation module, the connecting pipe communicates with the coolant heat radiation module and the fins, and the return pipe communicates with the fins and the air conditioner indoor unit;
• a control valve assembly connected with the output pipe and controlling an opened-closed state of the first circulation pipeline;
• a heating pipeline communicating with the output pipe and the fins, communicating with the return pipe, and further connected with the control valve assembly, wherein the control valve assembly controls an opened-closed state of the heating pipeline;
• and
• a heating assembly connected with the heating pipeline and configured to heat a coolant in the heating pipeline before entering the fins, wherein
• in the heating process, the first circulation pipeline is opened through, and in the defrosting process, the first circulation pipeline and the heating pipeline are both opened through, and the heating assembly is started.