What is the function of the Jetta small coolant reservoir?

[Sandy]

Jetta small coolant reservoir serves to replenish the antifreeze. Most vehicles utilize water-cooled engines, which rely on the continuous circulation of coolant for heat dissipation. Within the engine, the coolant follows two circulation paths: a major cycle and a minor cycle. When the engine is first started and its temperature remains low, the coolant engages in the minor cycle. Once the engine reaches its normal operating temperature, the coolant switches to the major cycle. Jetta is an automobile brand under FAW-Volkswagen Automotive Co., Ltd., officially launched in February 2019 at Volkswagen's headquarters in Wolfsburg, Germany.