T503 Chiller Temperature Controller – 24VDC Replacement

T503 Chiller Temperature Controller

Restore temperature control and monitoring in a compatible refrigerated water chiller with this replacement T503 controller.

The T503 is a digital temperature controller used in compatible industrial water chillers for CO₂ laser machines. It reads the coolant and surrounding air temperatures, displays the current water temperature, and controls the chiller’s compressor and solenoid valve as cooling is needed.

This controller supports both intelligent and constant-temperature operating modes. It also provides visual and audible warnings for temperature problems and sensor failures.

How the T503 Controller Works

The T503 monitors information from two temperature sensors: one measuring the circulating coolant and another measuring the surrounding room temperature.

Based on those readings and the selected operating mode, the controller switches the chiller’s refrigeration components on and off to help maintain the required coolant temperature.

Two Temperature-Control Modes

Intelligent Temperature Mode

In intelligent mode, the controller automatically adjusts the target coolant temperature based on changes in the surrounding room temperature.

This helps keep the coolant within a controlled range of the room temperature and may reduce the chance of condensation forming on the laser tube and coolant lines.

Constant-Temperature Mode

In constant-temperature mode, the controller works toward a fixed temperature selected by the operator.

This mode may be useful when a specific coolant temperature is required regardless of normal changes in room temperature.

Key Features

• Replacement controller for compatible refrigerated water chillers
• Digital water-temperature display
• Intelligent temperature-control mode
• Constant-temperature-control mode
• Controls the compressor and solenoid valve
• Monitors water and room temperature
• Adjustable temperature and alarm parameters
• High and low water-temperature alarms
• High room-temperature warning
• Room-temperature sensor failure warning
• Water-temperature sensor failure warning
• Audible alarm buzzer
• Cooling and operating-status indicators
• Four-button control panel
• 24VDC operating power

Control Buttons

• Up: Increases values and moves through available settings
• Down: Decreases values and displays the room temperature during normal operation
• SET: Opens or confirms temperature and parameter settings
• RST: Saves changes, exits the settings menu, or returns the controller to normal operation

Product Specifications

• Model: T503
• Product type: Digital chiller temperature controller
• Operating voltage: 24VDC
• Voltage tolerance:-20% to +10%
• Rated power consumption: Less than 3W
• Panel mounting opening: 71 × 29mm
• Temperature display: Three-digit digital display
• Display resolution: 0.1°C
• Sensor inputs: Two NTC temperature sensors
• Sensor rating: 10kΩ at 25°C
• Compressor relay output: 16A
• Solenoid valve relay output: 10A
• Control modes: Intelligent and constant temperature
• Controls: Up, Down, SET, and RST

Alarm Functions

The T503 controller can display alarm codes for several operating problems, including:

• High surrounding room temperature
• High coolant temperature
• Low coolant temperature
• Room-temperature sensor failure
• Water-temperature sensor failure

When an alarm is active, the controller alternates between the error code and the current water temperature. Pressing a button can silence the buzzer, but the alarm display will remain until the cause of the problem is corrected.

Compatibility Notice

This controller is intended as a replacement for chillers originally equipped with a compatible T503 controller. It is commonly found in certain CW-5000 and CW-5200 refrigerated water chillers, but compatibility may vary by chiller manufacturer, production date, wiring configuration, and controller version.

Before ordering, compare the following with your original controller:

• T503 model number
• 24VDC power requirement
• Panel opening dimensions
• Rear terminal arrangement
• Sensor type
• Wiring connections
• Compressor and solenoid relay ratings

Do not select a replacement controller based only on the appearance of the front panel.

Important Installation Information

Disconnect the chiller from electrical power before removing or replacing the controller.

Label or photograph every wire before disconnecting the original controller. Incorrect wiring may prevent the chiller from operating properly and can damage the controller, refrigeration components, sensors, or connected laser equipment.

Installation should be completed by someone familiar with electrical wiring and refrigerated water chillers.

After installation, confirm that the controller displays the correct water temperature, responds to both temperature sensors, and properly controls the refrigeration system before operating the laser.

Confirm Compatibility Before Ordering

Not sure whether this is the correct controller for your chiller? Contact Rabbit Laser USA with the chiller model, voltage, and a clear photo of the front and rear of the original controller. Our technical support team can help confirm compatibility before you order.