Capacitor Replacement

CapacitorCapacitor Repair for Air Conditioners and Heatpumps

Description: This is the procedure and information for replacing a capacitor on an air conditioner. The specific unit in this example is a carrier brand ground level, split straight cool system. This procedure applies to almost every air conditioning and heat pump system on the market.

What does a repair like this cost: This is a tough question to answer accurately. A lot depends on the area you live in, the company, flat rate vs. time and material and many other factors. I have seen prices as low as $120 and as high as $300. Capacitors for this repair are pretty inexpensive. It is a great candidate for a do it yourself person or someone just looking to save a little cash.

Why do I need this repair? Capacitor failures are very common. A bad capacitor can go unnoticed for a long time or at least until it dies completely. If they are not properly checked or an observant technician sees the signs of a capacitor on the verge of failing, a typical capacitor failure will cause a motor to not have the extra kick to get to start spinning. A weak capacitor will also cause a motor or compressor to run higher amps aka use more electricity. This causes them to run hotter and shortens their life expectancy. If you are lucky you have a dual run capacitor and both the compressor and fan motor will not start. If the fan motor capacitor is the only capacitor to fail, it will cause the compresser to go out on high pressure. If you have high pressure protection it will shut the compressor off before it goes into by-pass. If you don't the compressor will go into bypass and run until it over heats. Now I have seen many compressors go through this process and survive but common sense says it shortens the life of the system every time it happens!

Estimated Repair Time: 20 minutes

    • Tools:
    • Nut Drivers/Screw Driver like this one
      nut driver
  • Wire Stripper/Crimpers
  • Not required! Gloves I prefer mechanics gloves.
  • Not required! Volt Meter
    Volt Meters


  • Capacitor New Capacitor.
  • Mounting Strap
    Mounting Strap
  • Not always Required! Connectors

Repair Process:

  • condenser at side of house Locate your condenser aka the out door unit. Here is the one we are working on today. It about 10 years old. It is the builder put in so we can be sure it is not top of the line.
  • disconnect location Turn off the disconnect. It is a good idea to check and make sure their is no power to the condenser with a voltage tester or meter. Here is our disconnect. It is a breaker type you man have the pull out type.
  • Condenser Cover Panel Find and open the access panel. A good clue if you air conditioning system has more than one cover. It is the one with the electrical warning sticker on it. Here is the one for this unit. It is held on by two screws but a trick to easy removal is loosening this top two screws too.
  • disconnect location Here is our capacitor. This particular one is a 45/5 microfraud dual run capacitor. Learn how to identify yours! Now if if the one you have doesn't match or for some odd reason we not will be able to make it fit. Lets stop here and get a different one. But please keep in mind it doesn't have to look exactly the same and rarely does. As long at the it is the right type, the connecting and mounting challenges are easy to overcome.
  • disconnect locationThe capacitor looks bad and tests bad. Learn how to test a capacitor here. What makes it bad. This particular one bowed at the top. This top of it should be recessed below the top edge and flat.
  • Here is the most challenging. It is really not that challenging. How do I get all the wires from the old capacitor to the new one?
    • First rule is make sure you know where they are coming from before you remove them. Now you can always use the schematic on the access but that is time consuming and you have to know how to read schematics. Sometimes they have worn off or rotted away. We are not going to attempt to cover this large topic here.
    • Capacitor designation markingsSometimes you can unmount the original capacitor and mount the new capacitor and transfer the wires one by one from the old one to the new one. The most common sense way is to draw picture and mark them. I personal do this in a simpler form. The top of the old capacitor is marked and can be used as the labels. The typical markings are C, Fan, Herm which means Common, Fan, Compressor, respectively.
  • removed capacitorRemove the old unit. Typically held by one or two screws. Now a quick side bar. Most often that mount will not work. This is why we have strapping.
  • turbo capacitor ready for installI like to use Turbo Capacitors as they fit in almost all systems and come rated for the higher voltages. However, they cost a bit more than the size size dual run capacitor. Get the proper size capacitor or set your turbo capacitor to the appropriate capacitance.Quick Tip: If you find a Turbo capacitor getting weak, you can adjust it to the next capacitance setting to extend it's life.
  • We are done now but some of the best advice I ever received was to measure twice and cut once. This applies here too. Double check all the wires are the connections are in the right place. in were they are suppose to be connected. Verify all the connections are tight. I like to give each wire a little tug at the base of the connection to verify this. Quick tip: If the your spade connectors are loose, pull them off, pinch them down just a little with your crimpers and reconnect them. This tip alone can save numerous failures. Loose connections cause failures
  • Thermostat Proceed to the the thermostat and turn it on so it calls for cooling. It is the same process you go through when you find your house to hot and you want it cooler.
  • Pulled In Contactor If all has gone well, the contactor should be pulled in. If your contactor is open, it would look like this. It is usually accompanied with a slight hum or buzz but not always. Most systems have a delay before turning the condenser on so be patient.
  • Put the condenser cover back on air conditioning condenser.
  • With the contactor pull in, turn the disconnect back on. The air conditioner will come on and run.

You just saved big bucks and extending the life of you air conditioning system!