My thermostat worked well on a Goodman with 4 wires for about 10 years and on the new Train with 4 wires for about a month.
The HVAC tech HAD to add a common wire. The thermostat worked fine until we had a Thunderstorm. I do not know if the thermostat will still work on 4 wires or not. According to the HVAC tech when the "low voltage" is connected, "it goes crazy".
When the Thermostats were installed about 10 or more years ago we were told to use 4 wire only. The system worked fine all these years through thunderstorms with out the C wire. I understand the thunder storm screws things up, with the C wire.
If there is a way to test the thermostat without being connected to the A/C. I want to make sure the thermostat is functioning correctly, stand alone.
