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. System is operating properly at this time. Today we talked about joining the maintenance program but customer was not interested at this time. View visual findings from this job here - https://visionshare.xoi.io/?id=XA-0D78-89D1C15BD8F74EECB43BCEB46CBE3823