Dispatched for 2 ac maintenance and 2 furnace safety checks. During the furnace inspection the furnace was operating for the first floor. During all furnace inspection we have a carbon monoxide detector operating during the inspection for your safety. After checking other components of the furnace the carbon monoxide detector start to detect CO in the air and continue to climb higher. At that point the system was red tag and gas turned off to the furnace. The second floor furnace components were in better condition than the first floor unit. There was no CO detected for this system. Only concern is the inducer motor. And signs of the ac coil freezing with water inside burner area. The 1st floor ac unit is operating with in manufacture specifications, the second floor ac is showing signs of a possible leak due to the refrigerant pressure not within range Thank you for allowing us in your house to provide the perfect home service and i look forward to y