Arrived on site to perform combo tune up on 13 year old system. Upon creating a time expectation, homeowner mentioned that she had to leave to work in a few and that her daughter will be home to take care of payment, wants me to email recommendations and pricing over to her so she can take a look at everything, and also mentioned that she does have a friend That she will run everything by and see if he can do any of the work for her. I cycled system for heat. Upon realizing that heat is not working, I brought it up to homeowners daughter and she was aware of the problem, she stated that it’s never worked and they have never used it, they only use the air conditioning. After further diagnosis found that thermostat is not sending the furnace heating signal and thermostat needs to be replaced. Still removed burners and assembly to inspect heat exchanger. No concerns at the moment still looks brand new. Cycled system for cooling. Checked furnace and condenser electrical and system compo