AlGreen
Member
For the past several days the AC for my upstairs has intermittently not responded to thermostat calls for cooling. I have two zones, with the upstairs one consisting of a Carrier Infinity 24ANB6 central AC, an old Lennox Elite G24M2 furnace, and Honeywell VisionPro 8000 thermostat. Those times when the AC isn't cooling, the Carrier is showing code 83 for low-pressure lockout, and the Lennox blower fan is making a humming sound but not spinning.
With the thermostat set to Fan: Auto and System: Cool (temp adjusted below threshold for cooling) I checked the AC voltage across the ACB Cool and Neutral terminals, and measured 12oV. Then (with power off) I checked the 5uF capacitor for the blower motor, and it measured spot on (ESR was also low-0.06 ohms). The blower wheel spins freely when I move it by hand. At this point, I feel fairly confident that the motor needs to be replaced, however, I'd like someone who has more experience with HVAC stuff to chime in and confirm.
With the thermostat set to Fan: Auto and System: Cool (temp adjusted below threshold for cooling) I checked the AC voltage across the ACB Cool and Neutral terminals, and measured 12oV. Then (with power off) I checked the 5uF capacitor for the blower motor, and it measured spot on (ESR was also low-0.06 ohms). The blower wheel spins freely when I move it by hand. At this point, I feel fairly confident that the motor needs to be replaced, however, I'd like someone who has more experience with HVAC stuff to chime in and confirm.