Crossflow fans ensure good air flow inside the microwave oven by:

1. Air intake: Crossflow fans are located in appropriate locations of the microwave oven and can intake air from the inside of the microwave oven. They are usually located at the back or side of the microwave oven and can intake fresh air from the environment around the microwave oven.

2. Internal air circulation: Once the crossflow fans intake air, they will exhaust the air to the inside of the microwave oven. This air loss helps to establish internal air circulation. The air is pushed to various areas of the microwave oven, including the heating cavity, heat dissipation components, etc.

3. Air contact with heat source: The crossflow fan pushes air to the heat source inside the microwave oven, such as heaters and electronic components. When the air contacts the heat source, it absorbs heat and carries it away in the form of hot air.

4. Hot air exhaust: The crossflow fan pushes the hot air that has been in contact with the heat source out of the microwave oven cavity. This helps to exhaust the hot air from the inside of the microwave oven and avoid heat accumulation inside the microwave oven.

Through air intake, internal air circulation, air contact with the heat source, and hot air exhaust, the crossflow fan ensures good air flow inside the microwave oven. This flow helps to disperse and ventilate, maintaining a stable temperature inside the oven and keeping the appliance functioning properly. They also help control the temperature and prevent steam from accumulating inside the oven, providing better cooking results.