Balancing report mismatch after VFD replacement: what I checked

After a VFD replacement on an air handler, the balancing report no longer matched what the BAS showed. The fan speed looked stable, the drive had no active fault, and the mechanical contractor said airflow should be close to the old setup. Facilities still complained that two zones felt weak during morning warm-up. I started with the basics: drive parameters, motor nameplate data, BAS command sig…