Problem: What do I look for when a capacitor is bad? My Air Conditioner unit will not do anything!
Answer: Capacitor problems are probably the second most common problem that I see every summer in our 28-year-old HVAC business! Air Conditioning and heat pump systems low on refrigerant charge are the most common problem that I see. Changing out a capacitor is a simple, inexpensive problem that almost all homeowners can fix easily if you are good with your hands and have the right capacitor. Weak or bad capacitors can also cause blower motors to not run or to run slow. We have three really good YouTube Videos near the bottom of this page that explain how to replace and troubleshoot an air conditioner’s capacitors. We also have a really good YouTube Video made by AC Service Tech that shows how to find the capacitor rating if the capacitor is rusted so bad that you can not read the specifications off the capacitor. We sell over 80 different capacitors on the following page: Please click here to see the capacitors we sell.
What to look for when a capacitor is bad:
The Air conditioner outdoor unit will not come on. Either the outdoor fan does not run, the compressor does not run, or both the fan and the compressor do not run. You have checked and reset your circuit breaker. The outdoor unit still does not come on. You can hear a little humming sound inside the unit which is the low voltage contactor humming. Please pull the disconnect and disconnect the power to your outdoor air conditioning unit.
*Please make sure your electrical power is off before working on any air conditioning equipment. You take the door or cover off your outdoor unit’s control box and find a bad, swollen run capacitor. EPA stopped allowing manufacturers to produce capacitors with cancer-causing PCBs. Since they stopped allowing the use of PCBs in the capacitors and now capacitors have a shelf life. Many times I see capacitor problems that will not allow the compressor or the fan to come on. Many times you can clearly see that the capacitor is bad because it is swollen or even blown apart with capacitor oil everywhere! Please see the pictures below. Sometimes you need a special meter to test the microfarad (MFD) or UF rating. A capacitor tester. Please click here if you are interested in seeing a real good Supco Capacitor tester.
“MFD” and “UF” mean the same thing, “Microfarad”. Many times you will see a “UF” rating on the capacitor instead of “MFD.” Yes, these two abbreviations mean the same. Most of the time you can tell that a capacitor is bad because it will be swollen up. Please see the picture below for the comparison between a good and bad dual run capacitor. We call them dual because the capacitor helps run both the fan and the compressor. If you have any questions please email us anytime or comment below. Our email address is: firstname.lastname@example.org
*Tip: When identifying the capacitor that you have, you might see the rating stated in “MFD” or “UF.” “MFD” and “UF” mean microfarad rating and mean the same. Below we have some pictures of bad round and oval capacitors. Sometimes capacitors are weak and need to be replaced. If you do not have a capacitor tester…I would suggest taking the capacitor to an appliance parts supplier and ask them if they would be kind enough to test the capacitor for you. Please click here if you are interested is seeing the over 80 different capacitors we sell. We would love to help you out and have your business!
Below we have a real good informative video which shows how to troubleshoot and repair an air conditioner’s contactor and capacitor. Thanks to Kevin Miller for making this informative video!
Below we have a real good informative and educational video on “Dual Capacitor Checkout Procedure” made by Ron Walker. Thanks so much to Mr. Walker for making this informative video!
Below we have a really good YouTube Video made by AC Service Tech that shows how to find the capacitor rating if the capacitor is rusted so bad that you can not read the specifications off the capacitor.