Checked all operations in the heating mode and inspected furnace filter. Filter was dirty and replaced with a customer supplied filter. Checked all electrical components and completed a combustion analysis of the furnace. Furnace was burning fuel properly at this time and all electrical components were looking good. System is operating properly at this time. Today we talked about installing an electrostatic filter but the customer has electrical issues so they are unable to do so at this time. View visual findings from this job here - https://visionshare.xoi.io/?id=XA-0D78-AACAAC991CED444F9A299C26B18E233A