Arrived to remedy an inoperable system. Found that the tip of the condensation line had frozen. Cleared this blockage and the system started up as designed. Spoke with homeowner and started a performance maintenance. Set up for combustion analysis temperature split and static pressure tests for each system. Found that the main system is operating with failing static pressure. Verified operation of all mechanical and electronic components of each furnace. Found that the inducer in each furnace is leaking. Cleaned the flame sensors and retested their performance. Checked blowers for cleanliness and to see if there is any play in the bearings. Checked each systems heat exchanger to ensure proper venting of flue gas. Found that the main floor system is corroded and has holes present where it is leaking condensation from the flue. If the heat exchanger can leak condensation then it is able to leak carbon monoxide. Performed an electronic gas leak search. Spoke with homeowner about the syste