Johnson Controls Sabroe UNISAB III 4214‑001 Refrigeration Compressor Display Controller Unit

Product Description

The UNISAB III 4214‑001 is an integrated control and HMI unit developed by Johnson Controls Sabroe for industrial refrigeration screw and reciprocating compressors. It adopts panel‑mount design with IP65 front protection, 24V AC/DC power supply, graphical backlit LCD and membrane navigation keypad. It is equipped with analog/digital I/O, CAN bus, RS485 Modbus RTU and Ethernet Modbus TCP interfaces. The built‑in control logic, data recording and fault diagnosis functions make it the core controller of the UNISAB III refrigeration control system, widely used as spare replacement parts for cold storage, marine and process refrigeration compressor packages.

Product Functions

• Local start‑stop operation, capacity regulation and setpoint adjustment for refrigeration compressors via front‑panel HMI
• Real‑time monitoring of suction/discharge pressure, temperature, motor current, oil parameters and running status
• Compressor safety protection: high discharge pressure, low suction pressure, high motor current, oil pressure and temperature protection with automatic load reduction or shutdown
• Multi‑compressor sequencing, load sharing and energy optimization for parallel refrigeration racks
• Alarm event logging, historical trend recording and fault waveform storage for maintenance troubleshooting
• Modbus TCP / Modbus RTU and CAN bus communication to upload data and receive remote commands from SCADA and plant control systems
• Password‑based multi‑level user authority management, configuration backup and firmware upgrade support

Application Scenarios

• Large cold storage and food processing plant ammonia refrigeration compressor rack control
• Marine vessels and offshore platform cargo refrigeration and air‑conditioning systems
• Brewery, dairy and meat factory process cooling and freezing equipment
• Chemical and pharmaceutical factories requiring precise low‑temperature process control
• District cooling stations and central chiller plant automation systems
• Spare replacement and technical renovation of aging Sabroe UNISAB III refrigeration control panels

Common Problems

• LCD screen blank or unit reboot randomly：unstable 24V power supply, loose rear connector, aging internal power capacitor or voltage drop during compressor startup
• Membrane keypad insensitive or failed：front panel seal damage, moisture ingress and long‑term wear of the touch buttons
• Communication intermittent dropout：CAN/RS485 cable shielding damage, missing terminal resistor, wrong Modbus address or ground loop interference
• False safety alarms without actual equipment fault：damaged PT1000 temperature sensor, 4‑20mA signal drift or corroded I/O terminal block
• Compressor capacity cannot be adjusted normally：incorrect control parameter configuration, output channel failure or actuator feedback signal loss
• Alarm history and configuration data lost：internal backup battery depletion or sudden power outage during data saving
• Cannot connect with upper SCADA system：Ethernet IP conflict, firmware version mismatch, wrong communication protocol selection or network port hardware damage