Arrived on site to perform fall tune up on a 2018 carrier system. Furnace and evaporator coil located in attic. Client stated no issues. As system and home where built 2 years ago and just moved in. Cycled thermostat and was good. Found filter dirty and client was gunna supply his own and replace. Found black flex ducting used okay condition. Blower assembly and wheel slight dust accumulating. Motor is good and amp drawls are good. inducer motor is good and amp drawls are in range. Heat exchanger good. Evaporator coil good. Drain lines are good. Flame sensor is showing some wear and discoloration of oxidization at this time. Found temperature rise to be at 61 degrees and heating and is above rated range on system. Air flow restrictions could cause system to heat up high as not enough air flow is entering system. Found voltage at 121.3 and system is Rated at 115v. No protection on either unit. Recommend adding surge protectors to prevent system getting damaged from electrical surges an