This tech tip video runs through how to trouble-shoot the variable frequency drive (VFD) on a rooftop unit when the blower is not running.
Here are some basic things to check:
Is the wild leg on L3?
Is there an alarm?
Is there a fault?
Is there a call for the blower?
Is there power to the drive?
Is there power to the motor?
Is there power to all legs of the motor?
To bypass the drive, power the unit down.
Figure 24 is mentioned at the 1:22 mark and figures 25 and 26 are mentioned at the 2:49 mark.
Contact the experts at B-Y with any questions!