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 checked and reset your breaker and the outdoor unit still does not come on. You can here a little humming sound inside the unit which is the low voltage contactor humming. You 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 PCB's. Since they stopped allowing the use of PCB's the capacitors now 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! Sometime you need a special meter to test the microfarad (MFD) or UF rating. "MFD" and "UF" mean the same thing, "Microfarad".  Many times you will see an "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. 

*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.

 

                  

 

Bad round dual capacitor on the            Bad oval capacitor on the left. Good oval

 

                      left. Good round capacitor on the         capacitor on the right.

 

                      right.

 Repair Your Air Conditioner or Furnace Yourself and Save!  

Please see our capacitor testing meter located near the bottom of this page.

For Your Information: It is OK to substitute a capacitor with a higher voltage rating. For example. It is quiet acceptable to substitute an existing 35/5, 370 volt capacitor with a 35/5, 440 volt capacitor. It is not acceptable to substitute and existing 35/5, 440 volt capacitor with a 35/5, 370 volt.

All Capacitors On This Page Are In Stock & Ready To Ship!

We Test All Capacitors We Sell With A Capacitor Tester to Make Sure They Are Up to Specs. Before Shipping.

 

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Above Dual Round Cap:    Above Dual Oval Cap:   Above Oval Capacitor Terminals:

The Dual Round and Dual Oval Capacitors perform the same, but you might have to change the mounting strap in your system if the mounting bracket does not match up in size. I use pipe strap and self-tapping sheet metal screws to make a bracket. Please be careful not to drill into your condensing unit's coil. 

 

 

Below are the Dual Round & Oval Capacitors with an opportunity for you to purchase:

 

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Oval Run Capacitors 370 Volt:  

 

Below we have listed various types of oval run capacitors. Many of the capacitors listed below are found on indoor blower motors and outdoor condenser fan motors.  Please click on the "Add to Cart" button if you would like to purchase. Thank You!

 

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Oval Run Capacitors 440 Volt:

 

 

 

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Bryant Carrier Thermal Start Kit

P421-4006

I find several of these Thermal Start Assist devices burnt out on Bryant & Carrier air conditioners and heat pumps during the summer months. They are compressor start assist devices so I decided to list them under "Capacitors." Below is a picture with an opportunity for you to purchase. The kit comes with wires, mounting bracket and instructions. The device is about 2" long, and 1 1/2" in diameter.

 

 

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HC91PD001 Bryant Carrier 3 MFD (uF) Draft Inducer Motor Capacitor

 

This capacitor was added by customer request. I find this capacitor on many Bryant Carrier Draft Inducers. This small capacitor is only about and 1" X 1" square. The capacitor has a mounting hole in the back that you can not see in this picture.

 

 

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Many times you can visually see that a capacitor is bad, but sometimes you need the help of capacitor tester. That is why we are offering this Supco Digital Capacitor tester for $98.00. This capacitor tester has a digital read out and tests capacitors from .01 to 10,000 MFD. This includes all types of start and run capacitors used in the refrigeration and air conditioning industries.The MFD10 is designed to meet all industrial specifications and service requirements. Below we have pictures with an opportunity for you to purchase:

 

 

 

Please always turn off all electrical power, and discharge the capacitor/capacitors (if working around capacitors) before attempting to inspect or repair any heating & air conditioning equipment. Check to make sure the electrical power is off with a reliable meter. I have never been shocked by a capacitor (knock on wood) and rarely see them discharge, but it is a good idea to discharge them before working around them. Please read below. It tells you how to discharge a capacitor.

 

Please read the following: 

 

How To Discharge The High Voltage Capacitor: The capacitor is discharged by creating a short circuit (direct connection) between the two capacitor terminals and from each terminal to chassis ground (bare metal surface).Please make sure that you are touching the insulated screw driver handle and not the metal part of the screw driver before attempting theis procedure.

1. Do this by touching the blade of an insulated-handled screw driver to one terminal, then slide it toward the other terminal until it makes contact and hold it there for a few seconds. (Sometimes this can result in a rather "pop!")

2. Repeat the procedure to create a short between each capacitor terminal and chassis ground.

3. If the capacitor has three terminals, use the same procedure to create a short circuit between each terminal and then from each terminal to ground.

 

Disclaimer: HVac Distributing assumes no liability for any incidental, consequential or other liability from the use of this information. All risks and damages, incidental or otherwise, arising from the use or misuse of the information contained herein are entirely the responsibility of the user. Although careful precaution has been taken in the preparation of this website information, we assume no responsibility for omissions or errors.