Nest Thermostat Has No Power To Rh Wire (E74 Error): How to Fix
If your Nest thermostat gives you an “E74” error code, it is notifying you that no power to the Rh wire is detected. When that happens, your first reaction might be to look for the HVAC technician’s telephone number. But is that necessary? Can’t you troubleshoot and fix the issue yourself? Usually, you can