I recently had my gas furnace cleaned and while the technician was here he told me that the capacitor on my furnace was close to the 10% level that says it needs replacing. He also told me that if I didn't replace it and it went bad then that could ruin my motor and I would have to replace the motor as well.

I just want to make sure that I am not being taken advantage of by this company. Since I'm asking, what makes a capacitor go bad and how long should one last? One last thing is how much do you think it should cost for a professional technician to replace the capacitor in the Charlotte NC area? Thanks so much for the info.

Yes, it will indeed burn out the motor. Age and load make them go bad. I have seen them last 2 years and 20 years. If you have a service tech replace, it will cost a service charge, parts cost and time, probably $200 DIY should be less than $50 and a pretty easy job. Discharge the capacitor and take it to an HVAC supply store. Make sure to note the wiring before taking them off. You will have 3 or 4 wires.

If you are charged $50 for a capacitor while the tech is there for routine maintenance, you are being over charged. It is rare for a single capacitor to cost more than $10. Labor, normally less than 5 minutes.