Performed furnace clean and tune; inspected the exhaust and intake PVC ensuring all connections were secured, removed and cleaned the burners along with the flame sensor, cycled the system on and checked gas pressures, as well as performed a combustion test verifying no CO in the airstream, and lastly replaced 213 aprilaire filter and thermostat batteries. Also took the time to cycle in the AC system just to verify operations I did find a rodents nest in the system. Due to the age, condition, and cost to repair I highly recommend looking into our options for this system. I do foresee issues this summer with the AC system. Job complete