What type of maintenance tasks can be performed daily on a Thermo King unit?

Daily maintenance tasks are crucial for ensuring the efficient operation and longevity of a Thermo King unit. Checking fuel levels and inspecting for leaks is an essential part of this routine. By monitoring fuel levels, technicians ensure that the unit has enough fuel for operation, preventing unexpected shutdowns. Additionally, inspecting for leaks allows for the early detection of potential issues that could lead to more significant problems if not addressed promptly, such as fuel wastage or environmental concerns.

The other options involve tasks that are not typically performed on a daily basis. Changing oil and replacing filters are considered more intensive maintenance activities usually scheduled at longer intervals, as they require specific tools and disposal considerations. Upgrading software and calibrating sensors, while essential for optimal performance, are not daily tasks but rather part of periodic maintenance or troubleshooting. Cleaning the exterior, while important for maintaining the unit's appearance, does not address essential operational components like fuel levels and leaks, making it less critical than the selected task.