I have several of new Trane AC fan coil units that use the old Comm 5 boards. Both the chill water and hot water valves are operated by 24v 50/60hz motors that are operated by PWM. I'm new to this and just got introduced to the Rover service tool to troubleshoot it. How is it that these AC motors can be powered by PWM. I was under the impression that only a DC motor can be powerd by PWM.
Looks like the days of troubleshooting with a meter and guages are over.