This presentation provides a concise overview of how to conduct a flawless hygiene inspection of cleanroom HVAC systems according to VDI 6022. It covers the specific hygiene requirements in controlled areas, key testing steps, and the evaluation of sensitive components such as filters, humidifiers, and airflow systems. Furthermore, typical sources of error encountered in cleanroom practice are identified, and strategies for reliably avoiding them are explained. Finally, the importance of complete and standards-compliant documentation for operators and service personnel is highlighted.