The Thermo King 1H64617001 (part 45‑2449) is an HMI controller/indicator panel for the SR4 Smart Reefer series, used to display temperature, pressure and fault codes in refrigerated trucks. Common failure modes on this unit include a burnt-out LCD backlight or power supply board, intermittent I/O communication with the refrigeration control module, and failure of the integrated microcontroller due to overheating or moisture ingress. First‑check steps: verify 24 VDC input voltage at the controller’s power terminals; inspect the LCD panel for visible cracks or backlight LEDs that are off; review any stored fault codes on the main unit or connected PLC for patterns such as “E01” (communication loss) or “E02” (temperature sensor error).[oss-gpt-20b]