Bryant
Fan-Only Command Not Activating Blower
Thermostat fan setting is ON or CIRCULATE, but the indoor blower does not run.
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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 G wire between thermostat and indoor control board, Fan function disabled or misconfigured in thermostat, Failed indoor blower relay on Bryant control board, Faulty indoor blower motor
How to Fix / Troubleshooting
Safety first: Turn off power to the furnace/air handler at the breaker before working on wiring or internal components.
Steps to troubleshoot:
- 1. Confirm fan setting: Set the thermostat fan mode to ON and wait a few minutes to see if the blower starts.
- 2. Inspect G wiring: At the thermostat and indoor control board, ensure the G wire is firmly connected.
- 3. Technician jumper test: A technician can jumper R to G at the control board. If the blower runs, but not when commanded by the thermostat, the thermostat’s fan output may be faulty.
- 4. Check blower relay and motor: If the blower does not run even with R-G jumpered, the control board relay or blower motor requires professional diagnosis and possible replacement.
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Repair Difficulty
Hard
4/5
Required Part
Bryant Furnace/Air Handler Control Board
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