Upon inspection of the customer's furnace that was producing a grinding noise when temperature was adjusted via Nest app, I diagnosed the issue as a failing ECM inducer motor. While the noise was intermittent during my visit, I was able to confirm the source when powering down the system. I thoroughly inspected the heat exchanger and found no significant issues with the secondary exchanger, though noted minor surface rust that was confirmed to be superficial. Provided customer with replacement options for the ECM inducer and arranged for service advisor to discuss complete system replacement given the unit's age.
