Could just be a Capacitor

So the blower motor or compressor isn’t working.  It could just be a capacitor.  A much more simple and less expensive fix.Capacitor

What is a Capacitor?  Capacitors are described as a device used to store an electrical charge, but let’s look at in a little different way.

In a car, a battery is required to charge the starter so the motor will start when you turn the key. Well, in the HVAC industry, we use capacitors to help start our motors and compressors. Much like car batteries, there are many different types and sizes we can choose from so always make sure to look at the service panel and get the correct specs.

Before removing the capacitor from the unit understand that capacitors can carry a very deadly charge, so always handle carefully.

Alright, so let’s get into it a little deeper. Todays’ electric motors need some help to get going, that’s where the capacitor comes into play. When the blower motor on your furnace kicks on it can draw a high amount of amps or power and in order to get this motor moving it needs help. So, unless you want to sit by your unit ready to spin the motor to get it going every time it needs to kick on, you’re going to need a capacitor.

Let’s say your motor requires 5 microfarads at startup, a 3 microfarad capacitor will not be strong enough and a 10 microfarad will be too much.  Follow the specs and replace like for like.

Here’s why: would you take a V8 car motor and put it in your furnace to start the blower motor? Of course you wouldn’t, that’s obviously silly. It’s the same as if you try using the wrong size capacitor without matching it to the specs, READ THE SERVICE INFO on the motor plate.  This is where the great people at Dey Distributing can help.  You can bring the old one or the unit model and they will help get you back up and running with the correct capacitor.

In some applications, you will have two different components that need a charge. For example: a compressor and a fan. In this case, dual run capacitors come into play. So let’s say your ac compressor has a 35mfd capacitor, and the fan has a 5mfd capacitor: Can only one side burn out?  Yes.  Actually, it’s very common for this to happen.

So, if  a dual run capacitor is not available you do have the option to use two separate capacitors as long as you don’t vary off of the specs. What you do is (with the correctly sized wire) jump connect one capacitor to the other. In other words, you may have a 35mfd capacitor for the compressor and a 5mfd for the fan motor that just share a common or ground wire.

However, if possible always use the correct one with both mfd specs on it.

The first signs of a capacitor going bad is the motor has power and wants to start, but just doesn’t have the umphhh needed to get going. So if you don’t change the capacitor right away and keep letting the motor/compressor keep trying to cold start, you are going to burn out your motor, or worse, your compressor. Also, be aware that you must have the correct tool to check a capacitor. 

So be smart and if you’re unsure, please call a professional to test and fix it properly.   And as always, the fine people at Dey Distributing are available Monday-Friday 8 a.m.-5:30 p.m. and Saturday from 8a.m.-12 p.m. 1-800-397-5339.

Thank you and be safe!


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