I performed a heating maintenance on two gas furnaces Ac units I did nor replaced the two 14x14x1 filters and one 14x20x1 filter homeowner has already replaced the filters I checked all electrical components on both units and I found on the furnace that is in the garage that the switch to turn it on and off was not working properly the homeowner provided another switch so I replaced it and it is working fine I checked the temp rises and checked the heat exchangers and checked the gas pressures and checked and cleaned the flame sensors everything is in good working order at this time.