1. When the household air conditioner heats, the refrigerant of the outdoor unit is pressurized by the compressor to become high-temperature and high-pressure gas, which enters the heat exchanger of the indoor unit (in this case, the condenser), condenses, liquefies and releases heat, and becomes liquid, which will heat the indoor air at the same time, thus achieving the ultimate goal of increasing the indoor temperature.

2. The liquid refrigerant is decompressed by the throttling device and enters the heat exchanger (evaporator at this time) of the outdoor unit, where it evaporates, vaporizes, absorbs heat and becomes gas, and at the same time absorbs the heat of outdoor air (outdoor air becomes colder).

3. The refrigerant that becomes gas enters the compressor again to start the next cycle. It is based on the above process that the heating of air conditioner is realized.