How To Buy and Replace a Furnace Capacitor

By | October 14, 2022

install new capcitor2
Purchasing a furnace capacitor and installing it is easy to do and falls into the do-it-yourself category.

Basic precautions need to be taken, mainly turning the power off to the furnace so as not to get shocked.

Furnaces can fall into three categories when it comes to capacitors.

  • Not have a capacitor at all. Some units do not use a capacitor to run the blower motor.
  • Have two capacitors called a Start and Run capacitor.
  • Have only a single capacitor. This is the most common design type.
  • Where Is a Furnace Capacitor Located?

    To find the furnace capacitor, the panel door to the furnace will need to be removed.
    York furnace door

    The capacitor will be located close to the blower motor since it is there to help the blower motor run and have wires coming from it.
    furnace blower motor capacitor

    How To Read Your Capacitor Voltage and MFD for a Replacement

    HVAC capacitors are rated by the voltage and the Micro Farads.

    Micro Farads are usually abbreviated “uf” and sometimes “MFD”.

    To buy a new one, the voltage and micro farad (uf) need to match. The packaging or size will only matter for fitting into the furnace.

    The side of the capacitor will have the voltage and (uf) on a label on its side.
    Here is a picture of a 5 uf, 370 volt capacitor. With these two numbers a replacement capacitor can be bought.

    Here is an Example Listed on Amazon
    Genteq GENTEQ – C305L / 27L570 GE Capacitor Oval 5 uf MFD 370 Volt 97F5705 (Replaces Old GE Z97F5705, 97F95702, Z97F5702), 5uf 370 Vac(VAC), 5X370 Run Capacitor

    As you can see it is rated for 5 Micro Farads (uf) and 370 volts. Any capacitor with the same voltage and micro farads can be used interchangeably.

    How to Replace a Furnace Capacitor

    1. Turn off all power to the furnace.
    2. Locate the capacitor usual close to the furnace motor.
    3. How Replace a Furnace Capacitor

    4. Take pictures of the wiring to reference back if needed.
    5. Disconnect the wiring.
    6. Remove any bolt holding the old capacitor in place.
    7. Insert and bolt in the new capacitor.
    8. Reconnect the wiring.
    9. Power on and test the system.

    Can a Furnace Capacitor Be Tested?

    Yes, testing capacitors are a part of heating and cooling troubleshooting and is done all the time. A multi-meter capable of reading Micro Farads will be needed. To learn how to test a capacitor click here.

Category: Furnace repair

About Aaron H. Benetti

Aaron H. Benetti an HVAC technician who has worked in the field since 1991. He began his career as an HVAC installer and later began doing troubleshooting and repairs. Around 2010, he began to write books on HVAC topics, mainly tutorials and how-to information. Currently, Aaron works as an HVAC tech and also writes many articles and posts for websites as well as books and videos on HVAC topics.

One thought on “How To Buy and Replace a Furnace Capacitor

  1. Dennis

    Our air handler fan motor is not turning on, despite AC compressor unit working fine. I also tried turning on heat to see if this could start the fan (just to see if the fan motor is “alive”). Our air handler unit is for both AC and gas furnace. The fan blade turns easily (by hand).
    There is NO capacitor for the fan motor. The unit is a Trane from 2003. Could you suggest a few common culprits to look at?


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