Arrive to home and customer had two units, one unit was maintaining 80° and had a 21° temperature differential the other unit it was 87 in the home and the unit was running and heating and cooling due to a bad nest thermostat. We installed this unit two years ago and customer change thermostat out a year or so back. I just remove the heating low-voltage wire so that they had cooling, and the customer is going to replace the nest thermostat. I did charge them the trip and diagnostic because this was not related to our install. I told them if they want us to install the nest thermostat it would be an hour labor.. Unit running at departure with a 23° temperature differential.