The average home HVAC system has a device inside of it known as a capacitor, which is used to store the extra power the system needs to activate and begin working right away. All appliances, including the air conditioning and heating units of a HVAC system, need this extra surge of power to turn on. If an appliance is not working or starting, then there may be an issue with the capacitor. Replacing the capacitor is typically a faster, less expensive fix than replacing the entire appliance. With the right tools, any individual can perform a simple test on their HVAC capacitor to determine whether or not this device is working properly. Since capacitors hold an electric charge, even when turned off, it is important that any homeowner looking to test this device exercises caution when performing this test. First, the following supplies are needed: Once you have all your materials and tools gathered, follow these instructions to test the capacitor. Start by unplugging the portion of the HVAC system that needs testing and turning off the power supply to the home's air conditioner.

Using the screwdriver, carefully remove the appliances' covering to access the capacitor. Take the flashlight and shine it inside the capacitor, near the device's two terminals. Upon visual inspection, if the capacitor is bulging, leaking, or discolored, then there is no need to test any further, as these are all signs that the capacitor needs to replaced immediately. If the capacitor does not exhibit any of the listed condition, proceed to the next step. Before testing any capacitor, it is important to drain the electrical charge from this device as unplugging the appliance alone will not drain the charge completely. Start by holding an insulated screwdriver out by the grip and placing the shank of the screwdriver across the two metal terminals across the front of the front of the capacitor. There may be a small spark the first time this is done. Repeat the process several times to ensure the charge is completely removed. Once this is done, use a pair of needle nose pliers to disconnect the capacitor from the wires.

All multimeters have capacitor settings on them meant specifically for users who want to check these electrical devices. Turn the dial on the front of the multimeter to the capacitor reading setting. Connect the two leads from the multimeter to the two terminals on the front of the capacitor. Take the black wire and attach it to one terminal on the capacitor and link it to the hole in the multimeter marked "com." The red lead should attach through the hole marked "cap." Allow the multimeter to render a reading. Take the time to check the front of the capacitor to determine what that individual device's proper capacitance level is. If the capacitance level from the multimeter reading is within 6 percent of the capacitor's desired rate, then the capacitor is fine. If it is higher or lower than this amount, then the device has gone bad and is no longer working properly. If a HVAC capacitor is no longer working, then it is time to replace this device. A variety of eBay sellers have replacement capacitors available right online, along with the multimeters and other tools needed to test this device.

When purchasing a new capacitor, make certain that it is the same size and has the same capacity as the one being replaced. Most individuals can follow the instructions that come with the capacitor to safely replace this component of their HVAC system. If replacing the capacitor does not work, then you may need to consult an HVAC specialist for a more detailed diagnosis.This tutorial specifically pertains to testing motor run capacitors or motor start capacitors. 1. Dis-connect power to test capacitorac power supply packaging Start by making the motor safe to test by disconnecting power. ac unit sound barrierIdeally, the unit should be unplugged, but shutting off a circuit breaker or disconnect may be adequate provided it can be locked out against accidental re-engagement. split wall air conditioner units

The test capacitor procedure must only be carried out after it has been verified that power is no longer present. 2. Check for residual voltage at test capacitor Whenever you plan to test capacitor condition or electrical value, it is a vital practice to remove any residual power that may still be stored. Using the metal blade of a screwdriver with an insulated handle will allow you to discharge any stored voltage by simply shorting the terminals of the capacitor. The test capacitor may emit a spark and a pop sound upon discharge. 3. Remove test capacitor from the circuit You'll need to remove the capacitor from the circuit before performing a test. Disconnect one or both terminals from the motor to the test capacitor to remove it from the circuit. Disconnecting only one side will perform the desired result but leaves the capacitor dangling from the motor, making probing a little more difficult. 4. Test Capacitor (basic DEAD-OR ALIVE) using an analog multi-meter (up to 150 microfarad's)

An analog multi-meter may be used to test capacitor condition for a dead-or-alive basic test. Start by setting the meter to "Ohms" at 1k scale. Conecting the probes to each side of the capacitor's terminals (measure across the capacitor as if it were a battery), you will be watching for a specific sequence of needle movement. Note: AC capacitors used for electric motors are non-polarized and therefore do not have a positive or negative terminal. It does not matter which terminal orientation you use to test capacitor condition. If the needle quickly starts at zero then rises in resistance as a charge builds, the test capacitor is likely still good. If the resistance falls to zero and does not climb, the capacitor is bad. If the capacitor has no continuity as in no connection across the terminals, the capacitor is also bad. 5. Test Capacitor (specific value) using a digital multi-meter Many mid level digital multi-meters provide the ability to measure actual capacitance value of a test capacitor.