Trane Intermittent Power or Firmware Instability

Thermostat randomly reboots or restarts during normal operation

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Loose thermostat sub-base connection, Intermittent R or C wire connection, Weak transformer causing voltage dips, Firmware crash

How to Fix / Troubleshooting

Safety: Turn off power before removing the thermostat.

  • Step 1 – Reseat thermostat: Remove the thermostat from the sub-base and firmly reinstall to ensure good contact.
  • Step 2 – Tighten wiring: Check that R and C wires are securely fastened at both the thermostat and indoor control board.
  • Step 3 – Measure voltage stability: With a multimeter, monitor R–C voltage while the system starts and stops. Large dips may indicate a weak transformer.
  • Step 4 – Update firmware: Connect to Wi‑Fi and install any available firmware updates.
  • Step 5 – Replace thermostat if reboots continue: Persistent random reboots with stable power usually indicate internal hardware failure.
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Repair Difficulty

Medium 3/5

Required Part

Trane Smart Thermostat or Trane Indoor Unit Transformer
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