What do you have to regularly check on the air compressor?

You answered correctly by choosing to regularly check the pressure line connection and the V-belt on the air compressor. According to German traffic rules and vehicle maintenance standards, the pressure line connection must be checked to ensure there are no leaks or damages that could cause a loss of air pressure, which is critical for braking systems. The V-belt drives the compressor, so it must be inspected regularly for wear or damage to guarantee proper operation. The speed governor, however, is not typically subject to regular checks in this context, so it is not part of the essential routine inspection for the air compressor. Regular maintenance of these components ensures the air compressor works reliably, which is vital for vehicle safety.