Came out to call for a customer concern about there system not operating properly. Customer stated that we were out recently for maintenance on the unit, and when we left, we had left the thermostat set to 50 on AC. Customer said it got cold in the home, so she turned it off. When she tried to turn it back on, it seemed like it was getting hotter in the home. I checked the thermostat and system over and found that when I set the thermostat to cool and turn the temperature down the AC and heat would run at the same time. Pin pointed it to a thermostat malfunction. After discussing with customer about what I found and about replacing the thermostat, customer stated she believes the last tech messed the thermostat up. I can’t confirm or deny that that’s actually what happened, but I went ahead and picked up a simple thermostat for customer and replaced it. Tested new thermostat functions, and everything worked properly. Customer has been using us for over 12 years, so I told her I would c