Abstract: Thermal expansion and contraction are common properties of engineering materials. The change of component length and volume caused by temperature change may lead to air conditioner failure. Such as the air-conditioning internal gear movement mechanism, due to temperature difference caused by uneven thermal deformation and stuck, or caused by excessive clearance, so skidding unable to drive, loss of its function. Or the air-conditioning outside the guide plate movement mechanism, heat deformation against the face frame, unable to guide the wind. And among them the most difficult problem, is the problem of abnormal sound caused by thermal expansion and cold contraction, is the difficulty of the air conditioning industry. Based on the principle of thermal expansion and contraction, the optimization of structure design, control logic, material optimization and production process are studied by using dimension chain analysis, the problem of heat expansion and cold contraction of the air conditioner is solved by optimizing the theoretical design and practical application.

Key words: Air conditioner, Heat expansion cold contraction, Abnormal sound