I just arrived at Ozuye (after a comfortable premium comfort flight thanks to my brother Arne) for some HVAC repair and installation. As with any job, having the right tools is essential, so on arrival I had the following tools delivered by Amazon;

On the left is a torque wrench. That allows nuts to be tightened with the right amount of force. In the blue case is a manifold gauge set, which allows me to measure the pressure on the HVAC lines.

Top right is a leak detector device, that can be used to look for leaks in the HVAC lines; it beeps when the nozzle is close to a leak.

Bottom right is an infrared temperature gun, so the temperature of the indoor units can be measured. It will also be useful to trace hot and cold spots in the home, as any surface can be measured from a distance.

The AC in the great room still works ok; I managed to get the temperature down to 75 from 85 within about an hour. But I suspect there could be a leak in that unit too, just less bad than in the master bedroom.

Tomorrow (Friday) the new dual zone AC unit will be delivered, which I will use to replace the one in the master bedroom and a ceiling unit will be installed in the upstairs bedroom.