Did a maintenance on a gas furnace. Clean the flame sensor and I also cleaned out the pressure switch. Cleaned out the burner compartment and the blower motor while cleaning the blower motor I noticed some some loose bolts so I tighten them up. Also I did an amperage reading on the inducer motor and the blower motor which both are in range of furnace specs. Also changed out customer supplied filter rack. Along with the customer supplied batteries for the thermostat. System is getting older and does have a lot of rust. Customer is thinking about getting it replaced before next season. System is operating properly at this time.