The Ondyne 2100 Dew Point Controller is a precision monitoring and control unit used in industrial processes such as refrigeration, compressed‑air systems, and environmental chambers. Common failure modes for this class of dew‑point controllers include power supply degradation (especially the internal DC regulator), input/output relay or contactor wear, and sensor drift or contamination on the temperature probe. Begin troubleshooting by verifying mains voltage to the unit’s input, checking the 12 V/24 V output rails with a multimeter, inspecting all relays and contacts for continuity, and reviewing any displayed error codes or LED status indicators before proceeding to internal board diagnostics.[oss-gpt-20b]