York 371-04478-004 KIT DIODE TD425N12KQFS01​

Model: YORK Assembly PART 371-04478-004, KIT, DIODE, Origin: USA, Packaging Label: Johnson Controls / Baltimore, MD 21237. The actual item inside the box is Infineon POWERBLOCK TD425N12KOF S01, which is a bolt-type high-power rectifier/rectifier-blocking diode module. It has a common cathode double diode structure. Among the three large bolt terminals, the middle one is usually the common cathode, while the two sides have two anodes. It also comes with an auxiliary small terminal.
This component is typically used in the DC circuit of York variable frequency water chillers VSD frequency converters, performing functions such as rectification, rectifier-blocking, or DC bus protection. If the module breaks down, becomes open-circuited, or has poor heat dissipation, abnormal DC bus voltage may occur, triggering VSD faults, preventing the compressor from starting, frequent overcurrent shutdowns, or even burning the power module.
When replacing, it is necessary to power off and wait for the bus capacitor to discharge completely. Clean the old silicone grease on the heat dissipation surface and tighten the bolts according to the specified torque. Check if the air duct and heat sink are dusty. When purchasing, verify whether the old module model corresponds to the York part number to avoid using substitutes with insufficient voltage or current margin.