Thermo King SR-4 Multi-Temp to Single-Temp Conversion
Thermo King SR-4 Multi-Temp to Single-Temp Conversion
A service few independent shops offer: we convert Thermo King SR-4 base controllers from multi-temp (Spectrum) configuration to single-temp operation. Ideal when a used Spectrum trailer only hauls single-temp loads, when zone equipment has been removed, or when a replacement controller arrived configured for the wrong setup. Published price $550.00 flat — we verify controller health first, reconfigure, and bench-test before it ships back.
Spectrum Zones No Longer Installed
Zone Alarms on Single-Temp Loads
Replacement Controller Configured Multi-Temp
- Controller Health Check Before Conversion
- Single-Temp Configuration & Bench Verification
- Flat $550.00 — 7–15 Business-Day Turnaround
Symptom Troubleshooting Guide
Multi-temp (Spectrum) SR-4 controllers expect zone evaporators and zone sensors that many trailers no longer carry — and a controller configured for hardware that is not there produces nuisance alarms and confusing behavior. Converting the base controller to single-temp operation cleans that up at the source. Every conversion starts with a full bench diagnostic, because a controller with hidden water damage or failing solder joints should be repaired before it is reconfigured.
| Symptom | Likely Causes | How We Repair It |
|---|---|---|
| Used Spectrum (multi-temp) trailer, but you only haul single-temp loads | The controller is still configured for zones the operation never uses | We convert the SR-4 base controller to a clean single-temp configuration and bench-verify it before shipping it back |
| Zone or sensor alarms for zones that are disconnected or removed | The multi-temp configuration expects remote evaporators and zone sensors that are no longer installed | Single-temp conversion removes the expectation of the missing zone hardware, eliminating the nuisance alarms at the source |
| Replacement SR-4 controller arrived configured multi-temp | Used and surplus controllers keep the configuration of the trailer they came from | We reconfigure the controller to match your single-temp unit and bench-test it before you install it |
| Not sure the controller is healthy enough to be worth converting | Water damage, corrosion or age-related faults only show up under a real bench test | Every conversion starts with a full bench diagnostic — if the controller also needs a repair, we quote it before doing any extra work |
Frequently Asked Questions
What does the SR-4 multi-temp to single-temp conversion cost?
The published price is $550.00 flat, which includes the pre-conversion bench diagnostic, the single-temp configuration and full bench verification. If the controller also needs a repair, we send you a quote for approval before doing any additional work.
What do I need to ship for the conversion?
Just the SR-4 base controller — this is a board-only service, so never ship the complete unit. If you want us to verify your HMI display together with the converted controller, ship the HMI too and we bench-test them as a set.
Can the conversion be reversed later?
In most cases yes — the conversion is a configuration change, not a physical modification, so the controller can typically be configured back for multi-temp operation. Tell us how the trailer is equipped and we will confirm before starting.
How long does the conversion take?
Standard turnaround is 7–15 business days from the day the controller reaches our Miami bench — the same as our repair service.
Will the conversion fix my zone alarms?
If the alarms come from zones the trailer no longer has (or never uses), yes — after the conversion the controller no longer expects that hardware. If an alarm points at a real fault inside the base controller itself, we catch it in the pre-conversion diagnostic and quote the repair first.
1-Year Warranty
Every Thermo King SR-4 Multi-Temp to Single-Temp Conversion ships back bench-tested and guaranteed fully functional on delivery, backed by a 1-year warranty on the repair we performed.
Start Your Repair Now- $150 Diagnostic — Fully Waived With Approved Repair
- 7–15 Business-Day Standard Turnaround
- Component-Level Repair (Save 60%)
- Miami-Based Facility