Trane 90-Ton Commercial Chiller Repair & Troubleshooting 08.26.26

Setpoint Services performed commercial chiller repair and advanced diagnostic service on a Trane Series R RTAA 90-ton air-cooled chiller in Austin, Texas. The Trane RTAA0904YK02A3C0DF chiller was experiencing intermittent shutdowns, including a “Starter Transition – Compressor A” fault that prevented Compressor A from consistently completing its starter and contactor transition sequence.

Troubleshooting of the Compressor A starter circuit led to replacement of all four auxiliary contacts associated with the compressor starter/contactor sequence. After the electrical repairs were completed, Compressor A successfully started and transitioned normally during subsequent testing, and the previous starter-transition fault did not reoccur.

Setpoint Services later returned for an after-hours emergency chiller service call after the Trane chiller experienced another intermittent shutdown. Further diagnostics determined that this shutdown was caused by the chilled-water flow interlock rather than the previously repaired compressor starter circuit. Testing of the IFM SN0150 flow-monitoring relay and flow-sensor circuit revealed an intermittent wire-break/fault condition capable of interrupting the chilled-water flow interlock and shutting down the chiller.

The flow-sensor connector and pins were inspected and serviced, and the threaded connection was securely reseated and tightened. The chiller was restarted and monitored with both compressors operating normally while chilled-water temperature continued pulling toward the 44°F setpoint. The intermittent flow fault did not return during testing, although additional repair or replacement of the flow sensor, connector, cable, or associated wiring may be required if the condition returns