What is the primary purpose of carburetor heat?

The primary purpose of carburetor heat is to prevent carburetor ice formation. In the Cessna 152 and other aircraft equipped with carbureted engines, the carburetor mixes air and fuel to create a combustible mixture needed for engine operation. Under certain atmospheric conditions, such as high humidity and low temperatures, moisture can freeze inside the carburetor. This ice formation can restrict airflow and disrupt the fuel-air mixture, leading to a decrease in engine performance or even engine failure.

Activating the carburetor heat introduces warm air into the carburetor, which helps melt any ice that may have formed and prevents additional ice formation. This is particularly crucial during flight operations at lower temperatures or in conditions where the risk of carburetor icing is increased.

The other options, while related to engine operation, do not accurately describe the primary function of carburetor heat. Enhancing engine performance and improving fuel efficiency can be secondary effects in certain conditions, but they do not convey the main reason for its use. Cooling the engine is also not relevant, as the introduction of heat is specifically to combat icing issues in the carburetor rather than to manage overall engine temperature.