An electrical device used to initiate the engine when the vehicle is started is known as a starter motor. This device engages a pinion gear with the flywheel, causing it to rotate when the ignition key is turned on. Once the engine begins running independently, the pinion gear automatically disengages, allowing the engine to operate on its own.

The A/C compressor is the central component of a vehicle's air conditioning system, powered by the engine. It plays a crucial role by compressing the refrigerant within the air conditioning circuit, enabling the system to effectively cool the vehicle's interior.