Not a Repair.
A Reinvention.
How a trusted customer relationship and cross-discipline field engineering turned a catastrophic VFD failure into a more flexible, visible, and serviceable 1,200-ton chiller.
A Failed Drive Created a Larger Decision
Should the customer restore the same proprietary configuration or use the failure as an opportunity to build a better long-term solution?
The Familiar Repair Would Have Restored the Same Limitations
The chiller's refrigerant-cooled VFD had failed severely. Replacing it through the original manufacturer was possible, but the repair would have returned the machine to the same proprietary architecture, expensive components, limited communication, and potential parts lead-time concerns.
The facility also needed better visibility. The existing controls provided limited information to the building automation system. Operators could start the machine, but they did not have the alarm detail and operating data needed to see a developing problem quickly.
Return to the OEM Configuration
Replace the failed power module and proprietary components, restoring the chiller largely as it had operated before the failure.
Modernize the Drive and Controls
Install an air-cooled VFD and modern controls platform that could improve visibility, BMS integration, serviceability, and future support options.
Our technicians had built a relationship with the customer over time and already understood the facility's equipment and controls challenges. That history allowed us to present both paths honestly and recommend what we believed was in the facility's best interest. The customer trusted our technicians to pursue the less familiar option because the recommendation came from an established understanding of their operation, not simply the failure in front of us.
A Modern Controls Strategy Built Around the Existing Machine
The underlying chiller remained a viable asset. Rather than discard the entire machine or return it to the same controls limitations, our technicians designed the new drive and controls strategy around its mechanical, refrigeration, electrical, and operational requirements.
Selected for the compressor's electrical and torque requirements, physical cabinet fit, and available conditioned airflow.
Configured to control the chiller and give operators access to useful alarms, status, and operating points.
Proprietary communication wiring and incompatible sensors were replaced for the new control architecture.
Bus bars were fabricated, bent, drilled, and fitted to connect the new equipment cleanly.
Existing fans, terminal blocks, and usable cabinet components were repurposed where appropriate.
Modbus communication gave the customer's controls provider better access to chiller data and alarms.
The Work Was Sequenced Before the First Component Was Removed
The value was not in adding complexity. It was in managing the complexity well. Compatible tasks were planned to move forward together so our technicians could use recovery and vacuum time productively while protecting the quality of the final installation.
Refrigerant was recovered while compatible sensor and wiring work moved forward.
The failed drive, obsolete controls, refrigerant piping, and incompatible wiring were removed.
Power distribution, cabinet support, airflow, sensors, and control wiring were reconfigured.
The drive, chiller controls, safeties, and BMS communication were tested together.
Functional Was the Minimum Standard
An early bus bar approach could have operated safely, but it did not meet our technicians' standard for the finished installation. New four-inch bus bar material was sourced, bent, drilled, and hand-fitted to create a cleaner result.
The cabinet was treated the same way. Existing components were reused when they supported the new design, but the wiring, airflow, mounting, and layout were rebuilt to function as one intentional system.
Future technicians need to be able to open the cabinet, understand the work, and service it confidently. A clean installation supports long-term reliability and reflects ownership of the finished result.
The VFD Was Going Into Position One Time
The new VFD weighed approximately 680 pounds. It had to move through narrow access between chillers, and the space did not provide a practical overhead rigging option.
Our technicians measured the cabinet, mounting points, wall support, and equipment path in advance. They developed a custom lifting approach and installed the support structure before the move began. Once the drive was lifted, it needed to land exactly where planned.
The Customer Gained More Than a Working Chiller
The retrofit restored the customer's critical cooling capacity while addressing limitations that a return to the original configuration would have left in place.
The engineered modernization cost approximately $35,000 less than the proposed OEM repair path.
The selected components provided a more practical path to restoring the machine than waiting for the original power module.
Operators gained access to alarms, operating points, status information, and remote monitoring capabilities.
Modbus integration gave the facility's controls provider access to meaningful chiller information.
The modern platform reduced dependence on proprietary boards and created more future support options.
Our technicians now have a proven approach that can make a similar future retrofit an estimated 30 to 40 percent faster.
Better Options Come From Better Questions
This modernization required refrigeration knowledge, electrical calculations, controls integration, fitting, fabrication, planning, and collaboration. It also required our technicians to challenge the assumption that the machine had to return to the same proprietary solution.
A failed component does not automatically mean the original configuration remains the best answer.
Mechanical, refrigeration, electrical, structural, controls, and BMS decisions must support one another.
The first successful retrofit becomes a repeatable capability that can improve future speed and customer value.
Watch the Modernization Come Together
See the demolition, custom fabrication, controls work, VFD placement, and final commissioning from the project.
Give Your Facility More Than One Option
When a critical chiller component fails, the familiar repair is not always the only responsible path. Oklahoma Chiller can help you evaluate the machine, compare realistic options, and choose the solution that best supports your facility.
This article was prepared by the engineering, service, and technical experts at Oklahoma Chiller, supporting commercial and industrial facilities across Oklahoma and surrounding states.