By synthesizing modulation and regulation into a single unit

Professional contractors utilize this valve bonnet kit to upgrade legacy terminal unit systems or replace failed components without replacing the entire valve assembly

Complete Installation Kit: Includes 2 set screws and 3 mounting screws to eliminate the need for additional hardware procurement

the bulb should be placed at the 4 or 8 o’clock position

technicians should refer to the original unit schematic or Carrier service manual for full integration details and terminal mapping

York 331-03478-605 Chiller Service Board Kit 321042-401 By synthesizing modulation and regulationThe York 331 03478 605 Chiller Service Board Kit is the verified OEM replacement for the obsolete 331 03478 101 and 331 03478 609 models. Engineered for high performance York YVAA, YVFA, and YAGK chillers, this Service Board Kit is critical for restoring HVAC control system integrity and system communication. For technicians troubleshooting chiller fault codes or "unit won\'t start" conditions, this control board maintains the precise operational