Out to perform annual maintenance. Split Trane system attic. With buetler smart vent that has been disconnected. Filter 20-30-1 looks good. Tested system zoning, upstairs by itself, then downstairs by itself. Downstairs has blow by into the upstairs vents. Still concerned about water in pan, too cool, today to test ac, need to come back out once it warms up in a month or two to test ac. Tested the furnace cycling thru stages ok at this time. Checked flame sensor ok. Burners clean. Newer unit that doesn’t run very much furnace looks ok. Biggest concern is going to be on air conditioning. Slight dust burning off when unit starts. We will need to keep an eye on the zoning, working for now. But it is original dampers. And, the water in drain pan.