The capacitor is kind of like a big fuse and it is what starts and stops the motor and it is about 2- 3” long and tubular in shape. It comes in different colors such as black, gray, blue, red, green, white, yellow and orange. It is full of chemicals and paper and when it loses its seal the paper inside starts to burn from the electrical wires heating up causing the capacitor to smoke and sometimes while it is smoking it might make a whistling sound. A capacitor is by far one of the inexpensive parts to replace on an opener unit. Most garage door field technicians carry capacitor at all times because it is a very common problem. If a garage door technician asses your garage door opener needs to be replaced because its smoking, then ask him just replace the capacitor and see if that solves the problem. If a new capacitor does not solve the malfunction then a new opener unit may be needed. Just because a capacitor has not started to smoke or make funny smells from heating up then it does not mean that it has not gone bad. Many times you can tell when a capacitor is bad. Some of the examples are but not limited to – you will hear the motor click when you hit a remote button or wall button, it will make a humming noise. The cause for the humming noise is that the motor cannot start and stop because that what the capacitor does and when the capacitor fails – the motor will not start or stop. If your capacitor is displaying any of these problems then you should probably replace it.
Thinking of replacing it yourself ?
If you plan to replace it yourself and you will need to take out the old capacitor and look for the numbers printed on the side. The capacitor numbers tells you what size of capacitor you will need. Some openers might require two capacitors especially if you have a ¾ HP opener unit. Remember if you are trying to replace the capacitor yourself the first thing you need to do is unplug the open unit or else you will most definitely shock yourself it doesn’t feel good and you could fall off your ladder or hurt yourself so be careful. There are also four wires that plug into a capacitor so you will have to remember where those 4 wires go when you install the new capacitor. The easiest way to do this is to loosen the screw that holds the capacitor in place and then let it hang from the wires that attach to it. Now put the new capacitor right up next to the old one and remove one wire at a time unplugging the wires from the old and plugging it in the same position on the new capacitor this will ensure you have the wires in the right place.