Where should the amperage reading of an indoor blower motor be taken during furnace heating operation?

Taking the amperage reading of an indoor blower motor during furnace heating operation is best done at the red or white wire on the motor because this location provides the most direct and accurate measurement of the current flowing to the motor itself. Monitoring the current at this point ensures that you are measuring the actual operational draw of the blower motor, which can help in diagnosing performance issues and verifying that the motor is functioning properly within its specified amperage range.

Measuring at the motor leads (red or white wire) directly reflects the condition of the motor under load, as it accounts for factors like voltage drop that may affect other measurement locations. This method effectively shows how much current the motor is consuming while it is actively operating, which is crucial for assessment and any necessary adjustments.

Reading the current at other locations, such as at the circuit breaker, may introduce inaccuracies due to potential resistance in the wires or connections leading to the motor. Similarly, while the blower relay may control the power to the motor, it does not provide as clear an understanding of the motor’s actual performance as measuring at the motor does.