If your home's central air conditioning system is blowing warm air through the vents, then the first thing that you should suspect is causing the problem is the start capacitor. Failure of this humble electrical component is a frequent cause of a malfunctioning air conditioning system. The good news for you, as a homeowner, is that a defective start capacitor is easy to detect and replace at a relatively low cost. Below is more information about the start capacitor and how you can remove the old one and install a new, working component:
What the start capacitor does
The start capacitor is able to hold a significant electrical charge in reserve for use whenever the air conditioner compressor and condenser fan start. Starting either of these components, especially the compressor, places a strain upon the system's electrical resources. By using a capacitor, there is no need for an increased voltage load to maintain operation.
How to diagnose a defective start capacitor
Fortunately, assessing the problem is usually simple. These following signs of start capacitor failure can help you make a clear-cut identification:
- The compressor continues to cycle on and off as demonstrated by a low, but distinct, humming sound.
- The condenser fan is able to be "coaxed" into starting when the blade is spun a few times using a long, thin stick.
- The central air conditioning system's copper line is too hot to touch comfortably.
If you notice any of the above problems, chances are excellent that the start capacitor is in need of a replacement item.
How to replace a start capacitor
Accessing the start capacitor is easy on most units, and you can perform the job within a few minutes once you have all your tools and materials lined up. Some of the tools you need include the following:
- Screwdriver
- Flashlight
- Nut driver set
- Non-conductive gloves
After you have everything ready, the next step is to begin working on the disassembly and reassembly of the components.
Step-by-step procedure
1. Disconnect all electrical power to the air conditioner - Working on an air conditioner connected to live power is a deadly accident waiting to happen. That is why you must always take a moment to turn off the power at the outdoor pull switch that is next to your unit. To do so, pull out the pull switch located inside the small electrical box inside the park. Be careful that you don't lose track of the pull switch.
2. Remove the electrical access cover to the condensing coil - Using your Phillips screwdriver or nutdriver, remove the few screws holding the access cover in place and carefully pull the cover away. Do not pinch or cut wires with the sheet metal, and exercise great care not to warp or otherwise damage the thin metal.
3. Locate the start capacitor - Once you have visual access to the inside of the electrical components inside the small box, look for a cylindrical device approximately 6 inches in length with several wires attached to terminals on its top. However, be sure not to touch the capacitor yet, as you may experience a terrific electric shock should you do so. Instead, put on a pair of insulating gloves and carefully slide the shaft of a screwdriver or other metal tool in between the capacitor terminals. This will discharge the residual current inside the capacitor without being a risk for making accidental contact.
4. Remove the start capacitor - After you are satisfied the start capacitor is discharged, locate the straps holding it in place to the wall of the panel. Next, remove the screws or bolts holding the capacitor down. However, before you proceed further, take a snapshot of the wire terminals on the top of the capacitor to help you remember where to replace wires. Once the photo has been taken, you can detach the wires from their terminals.
5. Install a new start capacitor - Installing the new start capacitor is simple, but be sure to purchase the proper replacement part for your system. Match the microfarads rating and voltage rating from the old part with new potential parts to ensure the capacitor will work. In addition, also be sure to count the number of terminals and that the number is equal to that of the replacement part.
Installation is simple once you have found the right part. To install, attach the new start capacitor to its mounting location inside the panel, then reattach wires while referencing the pattern you photographed. Close up the electrical panel by replacing its cover, then restore power to the system by reinserting the pull handle.
If you feel you cannot do this by yourself, if you have any further problems, contact a professional air conditioner specialist in your area, such as those at Arnold Service Co.
