What condition must be checked regarding the air lines of the air compressor?

The condition regarding the air lines of the air compressor that should be checked is that there are no leaks and that they are made of metal. Ensuring there are no leaks is crucial because air leaks can reduce the efficiency of the braking system, leading to inadequate braking pressure and potential safety hazards. Metal air lines are preferred because they are more durable and less prone to damage compared to rubber or plastic lines. This robust construction helps prevent issues such as punctures or abrasions that could lead to failures.

This focus on leaks and material choice is vital for maintaining the integrity and reliability of the vehicle's air brake system, which is essential for safe operation. Checking for visible corrosion and rust, loose connections, or excessive wear, although important in other contexts, is not as foundational as confirming the lines are leak-free and constructed from suitable materials. These other factors may contribute to the overall condition but do not encompass the essential checks that ensure immediate functionality and safety of the air compressor air lines.