If your air conditioner isn't turning on, then you are likely facing one of several possible problems. However, a common problem with central air conditioning units is a failure of the dual run capacitor. This part is susceptible to a breakdown, which can occur at any time. The good news is that most homeowners can evaluate the dual run capacitor on their own and replace it if needed. Below is more information on dual run capacitors and how to determine if a dual run capacitor is broken:
What does the dual run capacitor do?
The dual run capacitor is located in the outside condenser unit and is designed to provide a "surge" of electricity during fan and compressor start-up. Both of these devices use an increased amount of current when starting, and without the extra boost provided by the dual run capacitor, the compressor and fan motors would not be able to turn over.
How to determine if a dual run capacitor has failed
There are several ways to evaluate a dual run capacitor and make a decision regarding its operational status. Fortunately, these tests are fast and simple, and they are safe as long as you exercise care when working. Below is how you can do it:
Step-by-step procedure for evaluating dual run capacitors
1. Disconnect power from the condenser unit - Since central air conditioning systems often operate on 240 volts AC, it is critical to disconnect the power to prevent a possibly fatal electrical shock. Most condenser units are attached to an electrical panel on a nearby wall, and you will find that disconnecting the power is simply a matter of pulling out a removable switch. Take out the switch handle and place it in a safe location for later.
2. Open the electrical panel - Once you have disconnected the power source from the condenser unit, locate the small electrical panel cover on the unit; it will be attached by sheet metal screws and covers the condenser unit's components. After taking off the panel cover, set it aside in the same location where you placed the removable switch handle in step 1.
3. Locate the dual run capacitor - After the cover is removed and the interior of the electrical compartment is in view, look for a cylindrical object with a thin metallic housing. The dual run capacitor has three terminals at the top end, which are in turn connected to wires. Do not yet touch the capacitor, as it should be discharged before you begin working. Otherwise, you may accidentally release a residual charge remaining and receive a nasty electrical shock.
4. Discharge the dual-run capacitor - To ensure there is no dangerous electrical charge in the capacitor, carefully lay an insulated flat head screwdriver across the terminal marked as "C" or "Common" and one of the other two terminals. If there is charge remaining, laying the blade on the terminals will short the capacitor and release its stored energy. Don't be alarmed if there is a sharp bang when the capacitor is cleared.
5. Examine the dual-run capacitor for visible signs of failure - The first step in evaluating the capacitor itself is to examine its outer metallic skin for bulging, as this is a tell-tale sign the capacitor has failed. In addition, if the dual run capacitor is leaking any oily fluid, then this is another sign of its failure and indicates a replacement is in order.
6. Test the dual-run capacitor for internal electrical integrity - After giving the capacitor an exterior examination, the next step is to use a multimeter to test for resistance and test current flow. Begin by disconnecting the wires from their terminals on the dual run capacitor, and tuck them aside. Next, set a digital multimeter to the oHms setting and attach the leads to the multimeter as directed by the manufacturer. With the multimeter turned 'on', hold the black lead attached to the 'Common' or 'C' lead. Next, touch the red lead to either of the two terminals. This will generate a readout of a number 1 if the capacitor is still in its normal operating range. If the numbers are consistently higher or lower, and don't quickly return to 1, there is a high probability the dual run capacitor is non-functional and will need to be replaced.
For more information on why your air conditioning system might not be working, contact a company like HomeSmart From Xcel Energy.