Person selling lennox 3.5 ton whisper heat 1992 furnace for 400.00 Replaced motor on blower 2 mon. ago w/new.A-coil and cover and some duct work included. Should we buy?
You are taking a chance that someting else may be bad or nearing breakdon.
A critical part of a forced hot air furnace is the heat exchanger. If ths develops a crack then you can get carbon monoxide into the house.
Another part that can give trouble is the pilot light or electronic ignition.
Finsally if something major does break, you have the cost of installing all over again when you buy a new furnace,
When cleaning anything including baby diapers, it is better to sweep off or scrape off as much solid and semisolid material as you can first. (1) Less cleaning fluid or detergent needs to be used, (2) Less of a mushy mess which in turn means that bleaches or disinfectants will be more effective.