Buying And Replacing A Furnace Capacitor

By | November 15, 2014

install new capcitor2
Purchasing a furnace capacitor and installing it is easy to do and fully falls into the do-it-yourself category. Basic precautions need to be taken, mainly turning the power off to the furnace as not to get shocked.
Furnaces can fall into three categories when it comes to capacitors.
1…Not have a capacitor at all. Some units do not use a capacitors to run the blower motor.
2…Have two capacitors called a Start and Run capacitor.
3…Have only a single capacitor. This is the most common design type.

Where Is The Capacitor Located?
To answer this question 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.
Capacitors are rated by the voltage 120 volt, 220 volt, and the Micro farads. Micro farads are often abbreviated uf and sometimes MFD.
To buy a new one the voltage and micro farad need to match. The packaging or size will only matter for fitting into the unit.
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

As you can see it is rated for 7.5 micro farads and 370 volts. Any capacitor with the same voltage and micro farads can be used interchangeably.
Can A Furnace Capacitor Be Tested?
Yes a testing capacitors are a part of heating and cooling troubleshooting and is done all the time. A multimeter capable of reading micro farads will be needed. To learn how to test a capacitor click here.



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