Blue shield plan fall service on 3 systems. Main home has upstairs and downstairs systems and bungalow in back yard has 1 system. Changed filters with blue shield plan. Downstairs has 1 14x24 1 16x8 and 1 16x20. Upstairs has 1 14x30 and outbuilding has a hig hair filter that I cleaned out and replaced. For downstairs Checked flue coil blower and cleaned flame sensor on downstairs. The system has a lot of construction dust in it, showed customer and explained that the house likely needs to have filters changed monthly instead of every 3 months. Cycled system on and inducer motor was making a rubbing sound. Unable to fix sound by taking unit off mountings. Continued testing amps, and gas pressure. Measured temperature rise and inside delta t. System is working in manufacturer range but needs a cleaning. Also spoke with customer about running sound. Customer wants to wait and not look into replacements at this time. For upstairs and outbuilding, both systems are air handlers. Checked