Building Utility Equipment Troubleshooting — real-world interview & field troubleshooting questions with clear, practical answers. Tap any question to open its answer. Showing the first 70 questions free. The complete 150-question set is available as a PDF below. HVAC, AHU & Ventilation Q1 The HVAC system is running but rooms are not reaching the set temperature. How would you troubleshoot it? Answer Check thermostat/setpoint, temperature sensors, chilled-water or refrigerant conditions, airflow, filters, dampers and fan operation. Compare supply and return temperatures; correct low flow, dirty filters, sensor error or control settings before checking major components. Q2 An AHU has very low airflow even though the fan is running. What should you inspect? Answer Inspect dirty filters, closed dampers, blocked ducts, fan rotation, belt condition and fan speed. Measure differential pressure across filters and verify the VFD or motor is receiving the correct command. Q3...