Inspected both humidifiers and found that the main floor humidifier is working properly at this time. The upstairs humidifier was not working. I found the wires to the humidifier were not connected. When I went to connect the wires, the AC wire popped out as well. I fixed the wiring and then the solenoid valve on the upstairs Humidifier did not open up. I checked the waterlines and then the valve opened up. Since it clogged before it has a high chance of clogging again. Main floor furnace is producing 6 ppm of carbon monoxide. When I ran a combustion analyzer, the test read higher numbers as well. The inducer motor is over amping and could give out at any time. I showed customer results of the complementary safety check. Customer opted to leave system as is at this time. Both furnaces and humidifiers are operating at departure.