Upon arrival to system no heat, I was shown to a split system located in the attic space. The homeowner had informed me that the system was operating well in the cooling mode but wouldn’t turn off and stayed in the heating mode. Upon inspection I found the thermostat to be in the off mode but still running the heating in the A/H unit. Even with the thermostat off I still had voltage going to the fan and the heat kit inside the unit. This thermostat has failed and needs to be replaced. Pulled out old thermostat and replaced with a new T6 pro and programmed to factory specifications. Cycled the system in all modes. System functioned properly and turned off when the mode was set to the off position. I’m highly recommending, pulling the fan motor and cleaning the fan wheel due to buildup on the wheel that’s causing stress to the motor. Cleaning this wheel can insure a higher system, efficiency as well as ensuring the motor isn’t overworking. Neither the indoor or the outdoor unit is