I have a voltage issue that cropped up today with one of my HVAC units at home. Whenever I try to call for heat, the second the relay trips, the Thermostat loses power and reboots. I pulled the head off and checked the voltage between the Rc and C wires. It shows a steady 27v. However, when I short the W to the Rc to trigger the heat pump the voltage quickly fluctuates around 11v to 24v and then cuts out to 0v. After a few seconds the voltage comes back and stays at 27v once I pull the the connection. I only did this long enough for the Fluke to capture the voltage as I know it’s rough on the compressor. I’ve read it could-be the High Limit on the Heat Pump. This doesn’t make sense as the unit was working fine till this evening.