Your video helped me in diagnosing a buzzing sound on one of my AC condenser during start up. The intermittent buzzing sound only happens when the fan motor is starting up and then the buzz would stop after about 5-6 seconds. After watching your video, I went out to take a look at the contactor. The reset button was stuck "in" an in position. I touched it with an insulated screw driveer and it was vibrating, even with the power disconnected. I assume that the capacitors were causing this vibrating. I moved the reset button a few times back and forth to make sure it moved freely. I have since ordered a new contactor. This contactor had a lot of dust on it from the dry AZ heat and if looked a bit worn, with some rust on the spring. I checked all 3 of my AC condenser units for this. I learned a lot from your video. Thanks...
Thanks for this important tip for aspiring HVAC . However I currently have a instructor who recommends not pushing in the "reset button" on contacts to do anything ! Now with that in mind , your presentation is still valuable , and I will try this next class when available in our labs.
In the video, for a trained technician the power would be on. I would not advise without proper training. Although with all power off, indoor and outdoor unit…you could Ohm across the contactors points.
