Arrived at a home goods store in San Joaquin County to complete their major AC maintenance. While checking in with the manager, our technician was alerted to an issue with unit #6 that services the offices. Brought all supplies up to the roof for maintenance and started services on #6 to help relieve the store. Found that the VFD had gone into alarm. Cycled the unit, brought back online and all parts were operating normally except for the VFD which went back into alarm. VFD has overheated and will need to be replaced. Bypassed VFD temporarily to bring #6 online again. Continued with the maintenance, service all remaining units and completing PM checklist. Will quote VFD replacement to customer.