How to Wire a Run Capacitor to a Motor Blower & Condenser HVAC WiringHow to Wire a Run Capacitor to a Motor | Blowers & Condensers – Sometimes when a blower or condenser fan motor goes bad a technician or even a DIYer has issues wiring the new motor and capacitor. Most motors come with clear instructions or a wiring diagram on the side, however, some people still struggle with the wiring part of the motor to the capacitor. It is important to get it right to prevent problems including burning up the new motor or even causing a dead short in the wiring and melting the wire. A PSC motor will run without a capacitor however it will run at higher temperatures pulling more amperage than design. Here we will illustrate the proper wiring for a motor to a run capacitor. 

How to Wire a Run Capacitor to a Motor Blower & Condenser HVAC Wiring

The above illustration does not cover every single type of motor wiring available on the market. However, motor and capacitor diagram represents a vast majority of motors and capacitor wiring available to the general public. As always, we recommend you thoroughly read the instructions that come with the new motor or capacitor to make sure you get it right. Get as much information as possible especially if you have never done it before. Not sure who said it but it goes like this, “those who fail to plan can plan to fail”. This is especially true in wiring things especially when you have no experience doing it.

There are several factors for single phase motors used in HVAC applications that should be observed when replacing a motor for a condenser or a blower. There are also factors that need to be observed when replacing a capacitor for an HVAC motor. We cover those factors in the linked to articles. Please observe those factors to make sure you get it right especially when wiring a new run capacitor to a replacement or existing PSC HVAC motor for a condenser or a blower.

Some of Capacitor and Motor Wiring factors include:
  1. Motor voltage rating
  2. Motor amperage rating
  3. Motor horsepower rating
  4. Motor rotation direction
  5. Motor casing usage
  6. Mounting brackets
  7. Motor run capacitor rating (MFD rating)
  8. Capacitor MFD rating
  9. Capacitor voltage rating

Additionally, some motors have more than one speed and will need to be wired properly to achieve the proper speed for the control settings. An example of this is a multispeed motor in an HVAC application will typically be wired to run slower for heating and faster for cooling. There are important reasons for this that can affect the comfort produced by the appliance. It may also affect the efficiency of the appliance so it is important to get it right. My first rule of thumb when replacing any part is to try and get an exact replacement part. With motors and capacitors, this is not always possible. In that case, you need to match it as closely as possible to the existing part to make sure it works properly and as designed.

How to Wire a Run Capacitor to a Motor | Blowers & Condensers - Wiring Methods, Tools, & Materials

You will also want to make sure you use proper wiring methods and make good tight connections. To do this you need the proper tools, wire, and wiring accessories. This includes connectors that will connect wire to wire and wire to a terminal. Female terminal connectors may be necessary to make a proper connection to the capacitor from the motor. It is important to make a proper connection from the wire to the connector and a tight connection from the connector to the capacitor. Failure to make a good connection can result in a failed connection and that could cause the motor to burn up.

How to Wire a Run Capacitor to a Motor | Blowers & Condensers - Motor Run Capacitor Wiring Diagram

Single Run Capacitor Wiring Diagram

Single Run Capacitor Wiring Diagram

The graphic is a reproduction of a Fasco motor I wired yesterday for a customer. It is basically self-explanatory. The only thing missing from this graphic is the motor rotation wiring which is a yellow and a purple wire that will reverse the direction of the motor depending on what direction is needed. Some are clockwise and some are counter-clockwise. Off the shelf PSC motors are generally set up to be wired for any direction you choose depending on the direction you need the motor to rotate.

Wiring an Air Conditioner Condenser Run Capacitor Compared to a Heat Pump Condenser Run Capacitor | How to Wire a Run Capacitor to a Motor

Air conditioners and heat pumps are different in certain ways. The air conditioner condenser will usually only run in the summer. While the heat pump condenser will run in the summer and the winter. The condenser fan motors in both are essentially the same except for how they are controlled. This means they will be wired differently in the condenser. The wiring for the air conditioner condenser fan motor will likely have the black wire (noted in the wiring diagram) go directly to the compressor contactor. The heat pump condenser fan motor will not. The wiring for the heat pump condenser fan motor will be slightly different. The black wire (noted in the wiring diagram) will likely be terminated on a control board. This control board is the defrost control board. It also controls the condenser fan motor in a heat pump. When a heat pump goes into the defrost cycle the condenser fan motor for the heat pump will shut down. This enhances and quickens the defrost cycle. Make sure you follow the wiring diagram for the heat pump to terminate the new condenser fan motor properly.

How to Wire a Run Capacitor to a Motor | Blowers & Condensers - Conclusion

Please read the directions for the new motor and how to wire the run capacitor to the motor. I have responded to calls where a homeowner got it wrong because they did not read simple instructions. It ended up costing more than if they would have called me in the first place. Of course, I do it all the time and can probably wire a capacitor to a motor in my sleep. However, when I run into something new, something I don’t have experience with, I pause to read the instructions so I get it right. When wiring a capacitor to a motor for your HVAC system that is good advice. Good luck!!!

Lastly, other Resources to help you with Capacitors and HVAC Motors:

High Performance HVAC

How to Wire a Run Capacitor to a Motor | Blowers & Condensers

To learn more about heating systems and HVAC use this resource.

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