I have a 10 year old Kenmore Furnace. I also have a 10 year old Kenmore A/C unit.

My A/C was set to 'auto' on the thermostat on the wall, but the A/C was not turning on when the temp in the house started to exceed the temp I had the thermostat set at. I can however get the blower to 'kick on' when I set the thermostat to 'fan on'.

The service tech I had come out, said I need a new blower motor and capacitor. Do I really need to replace them both? Is this my only recourse to correcting this problem? If so, what would be a fair replacement price for this (incl parts and labor)?

The Kenmore model number for the furnace is NTC6100GFA1

Usually if you replace a motor you replace the capacitor as well... price depnds on motor, time, labor and area where you live. I have charged from $450 to $1000 for blower motors. There is no way to say what the price is going for where you live.

I think you are misunderstanding the technician. When the thermostat is set to auto, the thermostat turns on the fan in the inside of the house, the compressor and the fan outside the house, when needed. When you turn the thermostat to "fan on" you are turning on the fan inside of the house only. Since the fan inside the house is usually an induction motor, it would not have a capacitor. Therefore, I can only conclude that the technician was referring to the fan on the outside. You will just have to believe the technician when he says "fan and capacitor". The capacitor is not an expensive item and is a good practice to replace along with the fan motor to avoid another service call next week.