keeping your HVAC system running efficiently

Do you know what it takes to keep your home heating system working efficiently? Most people know that the filters need to be changed from time to time, but exactly when should you be changing them? What type of filter should you be using? Is there anything else that homeowners can do to ensure that the system they rely on to heat and cool their homes operates using as little energy as possible? My blog will show you all sorts of things about maintaining your home heating and cooling system. In the end, you will know just what to do to take care of your home's system.

How To Discharge An Air Conditioner's Start Capacitor Ahead Of Testing


Central air conditioning units involve several electrical elements that keep the moving parts working as the refrigerant fuel moves through the system. One of those electrical elements is the start capacitor, which helps start up the system when you turn down the thermostat. 

If your air conditioner has stopped cooling efficiently or altogether, the unit might have a failing or failed start capacitor. You can test the capacitor yourself with an ohmmeter or multi-meter with a capacitor setting. But first you need to take a couple of precautions that will keep you from electrocuting yourself and/or blowing a fuse.

Capacitors hold a charge even after the power is turned off to the unit, so you want to discharge the capacitor before testing with an ohmmeter. If you don't feel comfortable performing electrical work, call in an air conditioning repair person for assistance.

What You Need:

  • Owner's manual
  • Screwdriver
  • Insulated pliers
  • Ohmmeter or multi-meter

Step 1: Cut Power and Access Capacitor

Turn off the electrical supply to your central air conditioner using the fuse box next to the outdoor condensing unit and/or turning off the main fuse inside your home. Consult your owner's manual to determine the exact location of your start capacitor, which is typically on or near the motor in the condensing unit.

Remove the condensing unit cover by either unscrewing the fasteners or lifting the latches that hold the grated cover in place. Set the cover safely to the side where you won't trip over it as you work.

Step 2:  Prepare the Capacitor

Locate the capacitor and use the insulated pliers to carefully remove the wires connected to the protruding terminals. Drape the wires carefully nearby so that you can easily replace the wires after conducting the test, if the capacitor isn't broken.

The capacitor should still have a bleed resistor wire attached. Use the pliers to position the resistor wire so that it lies over both terminals.

Step 3: Discharge the Capacitor

Turn your ohmmeter or multi-meter to the AC setting and attach the probes to the ends of the capacitor terminals. Wait until your meter's AC reading drains down to zero, which signals that the capacitor is fully discharged.

You can then proceed to testing the capacitor by switching the meter over to Ohms and checking the reading. If the number stays at zero or leaps into high numbers quickly, you need to replace the capacitor.


21 December 2015