A thermostat housing in a car is an essential component of the cooling system. It is responsible for housing the thermostat, which is a valve that regulates the flow of coolant through the engine. The housing is typically made of metal and is located near the engine, connected to the radiator hoses.

The main function of the thermostat housing is to provide a secure and sealed enclosure for the thermostat. The housing ensures that the engine coolant flows at the optimal temperature to keep the engine running efficiently. It also helps to maintain a consistent engine temperature by allowing the coolant to circulate when needed and blocking flow when the engine is cold.