Peak Thermo King
Thermo King Controllers and Control Modules
Thermo King controllers manage temperature control, operating modes, defrost logic, system protections, and alarm history. When a unit is not holding setpoint or throws repeat alarms, controller inputs, sensors, harness integrity, and output commands are often key parts of the diagnostic process.
Controller Models and Capabilities
Different controller families support different trailer configurations and operating needs. The best path is to confirm unit model and configuration, then match the correct controller or control module for reliable operation.
SR 4 Smart Reefer Controller
SR 4 is a microprocessor control system used on many Thermo King trailer applications, including single temp and multi temp setups. It provides fast access to operating information, supports temperature control logic, and works with compatible monitoring and telematics configurations depending on how the unit is equipped.
- Supports common trailer refrigeration operating modes and setpoint control
- Built for clear status visibility and alarm history review
- Available in single temp and multi temp controller variants depending on application
SR 3 Controller
SR 3 is a widely used controller platform designed for transport refrigeration control and monitoring. It supports a familiar, menu based interface and is commonly used across fleet operations that want consistent driver experience.
- Menu driven interface built for quick driver adoption
- Supports configuration options based on unit setup
- Often paired with control modules that manage sensors and outputs
SR 2 Controller
SR 2 remains common across many fleets. It supports core temperature management and unit control functions, and it is often seen in fleets prioritizing standardization across equipment generations.
- Common across legacy and mixed fleet setups
- Supports consistent temperature management and unit operation
- Replacement options depend on unit model and configuration
Control Modules and System Communication
Many controller issues are actually power, ground, sensor, harness, or communication problems. Control modules and wiring integrity matter because the controller can only operate correctly if it receives accurate inputs and can command outputs reliably.
- Sensor accuracy and wiring condition directly impact temperature control
- Intermittent faults are often harness, connector, or power related
- Correct module matching prevents repeat failures and downtime
Common Controller Related Symptoms
Controller symptoms can overlap with refrigeration or electrical problems. If you see these issues, a full diagnostic is the fastest way to confirm root cause.
- Blank display, dim screen, or unresponsive keypad
- Repeat alarms that return after resets
- Incorrect temperature readings or recurring sensor faults
- Mode or setpoint issues that do not hold consistently
- Intermittent shutdowns with no clear mechanical pattern
Controller Diagnostics, Repair, and Replacement
We focus on confirming the issue before replacing parts. That typically includes verifying power and ground integrity, checking harness and connector condition, validating sensor readings, reviewing alarm history, and confirming command outputs. If replacement is needed, we match the correct controller or module to your unit configuration and verify operation after install.
Controller FAQ
How do I know which controller my Thermo King unit uses
Controller type depends on the unit model and how it is configured. If you reach out through /contact with your unit information, we can help confirm the correct controller family and compatible modules.
Is it a controller problem or a sensor problem
Symptoms often overlap. A good diagnostic verifies sensor readings and wiring integrity, then confirms controller outputs and alarm history to identify the true root cause.
Can I upgrade an older controller
Upgrade paths depend on unit model, harness compatibility, and fleet requirements. In some cases a direct replacement is best, and in other cases an upgrade may be possible with the right parts and configuration.
Contact PEAK Thermo King & Trailer Services
Need trailer repairs or transportrefrigeration services? Contact us today to schedule service, request a quote, or discuss your fleet’s needs.