How To Replace the Thermal Overload Protector on an AO Smith Motor


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The Thermal Overload Protector on a motor monitors both motor temperature and current. When either exceeds the motor's limit, the Protector will shut the motor off until it cools. Overheating or high current are generally caused by other factors that overload the motor, like substituting the wrong motor or lack of proper ventilation around the motor. Occassionally, however, the Thermal Overload Protector goes bad and must be replaced. This guide shows you where the Thermal Overload Protector is located on a typical AO Smith motor, and how to replace it.  This guide is specific to an AO Smith motor but many of the steps are applicable to other makes.

Click here to view A.O. Smith motor parts. 

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 THERMAL OVERLOAD PROTECTOR - This picture shows the location of the Thermal Overload Protector within the electrical components of the motor.

Step 3

DISCHARGE CAPACITOR - Pool Pump Capacitors store an electrical charge that can shock you even when the power is off. Before removing the capacitor, discharge this energy by placing a screwdriver across the leads of the capacitor. CAUTION: Capacitors have been known to explode when shorted out. For your protection wear eye protection and place a cloth over the capacitor before shorting it out.

Click here to view A.O. Smith motor parts. 

Step 4

PULL OFF CAPACITOR - Remove the single screw that secures a clip holding the capacitor. Note how the plastic strip is positioned between the clip and the capacitor. It will have to be replaced in this position to keep the capacitor from shorting out on the motor.

Step 5

PULL YELLOW LEAD - Using a pair of needle nose pliers, remove the yellow wire to the Thermal Overload Protector from the capacitor.

Step 6

REMOVE BLACK PLUG - The operational voltage is set by positioning the black plug so that its arrow lines up with either 230V or 115V. Note where the plug is set then lift the black plug off of the Terminal Board.

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Step 7

REMOVE BLACK WIRE FROM PLUG - The Black Plug is attached to two wires, one black, one white. Remove the black wire by sliding out its terminal clip from the Black Plug.

Step 8

UNSCREW TERMNAL BOARD - Remove the two screws that secure the Terminal Board to the motor.

Step 9

LIFT OUT TERMINAL BOARD - With the two screws removed, the Terminal Board should lift off the motor. Three wires are attached on its backside.

Click here to view A.O. Smith motor parts. 

Step 10

REMOVE BLUE WIRE FROM TERMINAL BOARD - Turn the Terminal Board over and, using a pair of needle nose pliers, remove the blue wire that goes to the Thermal Overload Protector.

Step 11

REMOVE THERMAL OVERLOAD PROTECTOR - The Thermal Overload Protector is secured to the motor with one screw. The other end fits into a post. Remove the screw and lift off the Protector.

Step 12

VIEW THERMAL OVERLOAD PROTECTOR - This is a picture of the Thermal Overload Protector with attached wires. If the Thermal Overload Protector does not come with the black plug, remove the white wire from the old plug and place the white wire from the new Protector into the old plug.

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Step 13

SECURE NEW THERMAL OVERLOAD PROTECTOR - Place the left side of the new Thermal Overload Protector against the post and secure the right side with a single screw.

Step 14

ATTACH BLUE WIRE TO TERMINAL BOARD - Attach the blue wire from the new Thermal Overload Protector to the open terminal on the back side of the Terminal Board. Just push it on.

Step 15

REATTACH TERMINAL BOARD - Turn the Terminal Board right side up and reattach it to the motor. Check that the wires passing under the Terminal Board are not pinched as you secure the Terminal Board.

Click here to view A.O. Smith motor parts. 

Step 16

ATTACH BLACK WIRE TO PLUG - Slide the clip at the end of the black wire into the open slot of the Black Plug.

Step 17

REATTACH BLACK PLUG TO TERMINAL - Reattach the black plug. Line up the arrow on the plug in the same position noted in Step 6.

Step 18

REATTACH YELLOW WIRE TO CAPACITOR - Reattach the yellow wire coming from the Protector to the open terminal alongside the other yellow wire terminal. It should just push on.

Click here to view A.O. Smith motor parts. 

Step 19

CLEAR YELLOW WIRE - Place the yellow wire on the left side of the post under the Capacitor so that it will not interfere with the spinning Governor.

Step 20

ATTACH CAPACITOR - Replace the Capacitor and screw the holding bracket down with the single screw.

Step 21

CHECK WIRE POSITIONS - Check that all wires are tucked in away from the spinning Governor.

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Step 22

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


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Anonymous  Posted: 10/27/2020 

everything looks good but pump only runs less than minute then calmly shuts off? not enough time to function?

InyoPools Product Specialist  Posted: 11/3/2020 

You should check the voltage reaching the motor and for any obstructions in the impeller. you can see instructions on how to do this in the following guides: How To Determine Why a Motor Won't Start or Shuts Off & Using the Proper Test Equipment to Troubleshoot Pool Motors

 Posted: 4/6/2020 

My capacitor wires sparked against the housing of the motor ..I have replace the capacitor and still no running motor I have power could it be the overload protector? Thanks

InyoPools Product Specialist  Posted: 4/7/2020 

If the capacitor was able to spark on the motor or pump housing, I presume you were already working on it? Was there an issue with the motor before the sparking incident?A guide that contains most of our motor troubleshooting help: Pool Motor Troubleshooting

 Posted: 12/27/2017 

AF Mustang - Make sure your have the right replacement capacitor. Call us if you aren't sure. Then check that you are running on the correct voltage and that your governor and switch are not stuck. If that is all good, you may have a damaged motor. Check for continuity in your motor windings.

 Posted: 12/23/2017 

I installed a new capacitor and discharged it before installation. No other wiring was disturbed. After reinstalling the cover, I turned on the circuit breaker and heard a loud POP. I took off the cover and the thermal overload protector plastic casing was in pieces laying in the bottom of the cover. The surge had also tripped the upstream breaker feeding this panel and one more. I don't want to replace the TOP without finding the source of the problem. Any idea what might cause the TOP to explode that way?

InyoPools Product Specialist  Posted: 1/9/2017 

Tom - Unfortunately, we do not sell thermal overload protectors. See if a motor shop or pool shop will give/sell you one off a broken motor or they may know where to find new ones.

 Posted: 1/8/2017 

i am needing to replace my thermal overload protector (cet40abm listed on part) and can not locate a part anywhere. HELP!!!! thank you in advance

InyoPools Product Specialist  Posted: 7/11/2016 

Mike - Unfortunately, the thermal overload protector only protects the motor against overheating. If you configure a motor for 115V and connect it to 220V the motor windings will fail.

 Posted: 7/10/2016 

Hi, I just plugged 115v Hayward Super Pump to 230 :-(. The pump stopped after 1 sec but there is no smell, no burning. Is there any possibility that the thermal overload protector trips and the pump still good? It can protect the pump from overvoltage?

 Posted: 5/16/2016 

Hey I purchased a superpump, and I couldn't get the jumper to fit. So in trying to do so the wires on it got disconnected. All this being said I have it wired without jumper. And with help I have got it this far, question is when I turn it on it makes a clicking sound. Any and all help needed!!!

InyoPools Product Specialist  Posted: 4/13/2015 

TOP - Have someone do a continuity check on the Thermal Overload Protector.

Anonymous  Posted: 4/10/2015 

How do you determine if the TOP is bad?

InyoPools Product Specialist  Posted: 1/6/2015 

Where to buy TOP - You are right. These Thermal Overload Protectors are hard to find. Found a blind contact on the internet that claims to have them at 888-794-2365. If that doesn't work, see if a motor shop or pool shop will give/sell you one off a broken motor or they may know where to find new ones.

Anonymous  Posted: 1/5/2015 

This is a great article, but I have just one small problem. Where in the world can I find a replacement Thermal Overload Protector for my AO Smith Pool Pump. I cannot find one anywhere. Any help is appreciated. Thanks.