45
Bryant Outdoor Unit Lockout (Multiple Faults Detected)

Bryant Evolution/Preferred thermostat shows code 45; outdoor unit locked out and will not run until power is cycled.

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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

Repeated high- or low-pressure switch trips, Compressor overcurrent events, Control board internal fault, Persistent communication errors

How to Fix / Troubleshooting

Safety first: Turn off power to the outdoor unit at the disconnect and indoor unit at the breaker.

Steps:

  • 1. Review fault history: On Evolution/Preferred thermostats, access the service menu to view detailed fault history. Note which specific faults (e.g., high pressure, low pressure, fan fault) caused the lockout.
  • 2. Address root cause: If previous codes indicate airflow issues (dirty coil, fan fault), correct those first (clean coils, check fan motor and capacitor). If low-pressure faults are logged, check filters and airflow and then call a professional for refrigerant diagnostics.
  • 3. Clear lockout: After correcting obvious issues, restore power and clear the lockout via the thermostat or by cycling power for 60 seconds.
  • 4. Monitor operation: Run the system through a full cooling cycle. If lockout recurs, do not continue resetting; this indicates a serious underlying problem.

Professional help: Repeated lockouts can damage the compressor. Have a Bryant-certified technician perform a full diagnostic, including pressure readings and electrical tests.

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Repair Difficulty

Hard 4/5
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