How To Replace the Start Switch on an AO Smith Motor


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This guide shows you how to replace a damaged Start Switch on a typical single speed A.O. Smith motor. This Start Switch is only used with motors that have a start circuitry to boost starting torque. See our overview guide on "How To Replace AO Smith Motor Parts - Overview" to see how the Start Switch operates with the other electrical components. Although this guide is written for an A.O Smith single speed, many of the steps are applicable to other models and speeds.

Things You'll Need

Step by Step


Step 1

REMOVE ELECTRICAL COVER - Remove the two screws that secure the electrical cover on the electrical end of the motor. Lift off the cover.

Step 2

LOCATE START SWITCH - This picture shows the location of the Start Switch within the electrical components of the motor.

Step 3

REMOVE START SWITCH - The Start Switch is secured to the end of the motor with a single screw. Remove this screw and lift the Start Switch off the end of the motor.

Step 4

REMOVE SWITCH WIRES - Remove the two wires connected to the Start Switch: a red wire comes from the motor power cable and a white with red strip wire comes from the Start Capacitor. Use a pair of needle nose pliers to lift off the connectors.

Step 5

ATTACH WIRES TO NEW SWITCH - Push the two wire connectors onto the new Start Switch.

Step 6

POSITION SWITCH ON MOTOR - Place the middle of the Switch on the post next to the Governor. NOTE: Make sure the yellow wire is position on the other side of the post under the Capacitor. If it's left where it is shown, it may get cut by the spinning Governor.

Step 7

ATTACH NEW SWITCH - Attach the Start Switch with the single screw. If your motor is produced before November 2001, this Start Switch may have to be adjusted for optimum operation. See our guide on "How To Adjust the V-Switch on a Hayward Super Pump Motor". After November 2001, the A.O Smith motors were produced with a no-adjust Switch.

Step 8

REPLACE ELECTRICAL COVER - Replace the electrical cover at the rear of the motor and secure it with two screws.


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InyoPools Product Specialist  Posted: 6/9/2017 

Anonymous (Start Switch) - Here is the link to our Start Switch page.

Anonymous  Posted: 6/8/2017 

How to buy one of this items?

Anonymous  Posted: 5/26/2017 

What would make this switch go bad? Will the motor start without it?
I have replaced my capacitor, with no help. Motor will not run. It has power and spins freely. It was working, I turned off the breaker to service the heater. When I flipped the breaker back on, nothing. No humming, no nothing.