Went for a furnace(s) maintenance call today. Started with the downstairs unit. Did a static pressure test, it passed. Changed the filter due to the old one being dirty. When looking at the inside of the duct work, I noticed a severe amount of dirt and debris. Did a carbon monoxide leak test, there was no leaks. Heat exchanger was in ideal condition. Temp split between the supply and return duct passed. Combustion analysis test passed. Inducer amperage and capacitor passed. Checked the gas fittings their was no leaks. Blower wheel was clean and blower motor amperage passed. Went to the upstairs unit. Did a static pressure test, it failed. Changed the filter, due to the old one being dirty. Did a carbon monoxide leak test, there was no leaks. Heat exchanger was In ideal condition. Combustion analysis test passed. Temp split between the supply and return duct passed. Checked the gas fittings, there was no leaks. Inducer amperage passed. Blower wheel was clean and blower motor passed. Tha