xi Safety Notes alert you to potentially dangerous materials and practices. Pro Tips provide you with advice and guidance that is especially applicable for on-the-job. Service Call Scenarios present on-the-job situations in which a service technician receives a description of a problem, tests the system, and provides a solution. Step-by-Step Procedures are highlighted throughout the textbook to provide clear instructions for hands-on service activities. You can refer back to these procedures easily. Thinking Green notes highlight key items related to sustainability, energy efficiency, and environmental issues.