The customer has a package cleaning. Was here for the air conditioner portion of the cleaning. Cleaned up the unit. Electrical is ok. Checked the refrigerant levels. The refrigerant levels are good. While testing the zone system thermostats. Found that the basement thermostat temperature would no longer adjust in the cooling mode. Replaced the thermostat with a T4. Cycled the air conditioner. The air conditioner is running normally at this time.