Recent Electric motor thermal overload switch diagnostic FAQs set #2

Frequently asked questions about the thermal overload and reset button on electric motors.

This article series describes how to find and reset the thermal overload button on an electric motor and we give suggestions for repairing hard-starting or non-starting electric motors such as on air conditioning condenser fans and blower fans.

Electric Motor Reset Button & Thermal Overload Questions & Answers

Questions & answers about the reset button or reset feature on electric motors, posted originally at ELECTRIC MOTOR OVERLOAD RESET - topic home page.

Also see ELECTRIC MOTOR DIAGNOSTIC GUIDE

On 2018-10-02 by (mod) - Hobard dishwasher motor reset button

Mike

Is there a reset button on a Hobart Dishwasher or how do you re-set the unit?

An authoritative answer from Hobart was not easy to find, though you might get help from the manual for your Hobart dishwasher.

I have not found a reset button.

Most dishwasher controls re-set by turning the control dial through its operating positions back to OFF - open the door and then re-latch it.

However a temperature sensor could be tripping off the dishwasher - try cleaning the sensor in the dishwasher - scrub with vinegar and a scrubby sponge - as that may fix the problem.

On 2018-10-02 by Mike

Is there a manual reset button on a Hobart 474837-00001 dishwasher motor

On 2018-06-27 by (mod) - the bird ate my electric motor thermal overload switch

Sounds like your motor is genuinely overloading perhaps you can go through the diagnostic steps that I've added to the article above

To the famous explanation

The dog ate my homework

We can now add the bird ate my thermal overload switch

On 2018-06-27 by Bird

My birds ate the thermal overload switch that’s why I had to get a new one the search protector is what is tripping not to switch

I was able to order another thermal overload switch and I paid a lot of money to have it overnighted but it keeps tripping

On 2018-06-25 by (mod) - don't try substituting a makeshift motor overload switch outside the motor

Bird

To have space to give a detailed answer I repeat your question and our reply at THERMAL OVERLOAD SWITCH REPLACEMENT

Let me know what questions remain and keep me posted.

On 2018-06-25 by hbirdkeeper - thermal overload switch for Marathon electric motor

This is the photo of the info on this is the photo of the info on the motor

I am a girl and don’t know the technical terms but I’m not afraid to try and fix

On 2018-06-25 by hbirdkeeper

The thermal overload button is not good on my order marathon motor can someone please walk me through how to wire it in bypass it or what I could use as a substitute because the parts place said I’ll be 10 weeks to order

On 2018-05-09 by (mod) -

I wouldn't think so JJ.

It does sound as if the motor is drawing high amps and tripping the breaker.

Keep in mind that a bench test of windings can be misleading - windings can move, open, or short when the motor gets up to speed. I'd put a clamp-on ammeter on the circuit and watch closely for a spike after 3 seconds.

The thermal limit switch in an electric motor monitors winding temperature and is designed to go from normally closed (NC) to "open" if the temperature at the winding exceeds the manufacturer's specifications. It's a rather simple device.

Let's test the thermal limit switch itself, out of the motor.

With the ambient temperature and the limit switch temperature under 85 degF, set the VOM to Ohms on the 1x scale.
The switch should be closed (conductive) (very low resistance) until the switch becomes hot.

If the switch has zero resistance it might be shorted. If it has very high resistance it's not working at all. (That wont' be your case).

These switches are typically a "snap action" device: the switch will be either open or closed. Only if a switch terminal or wire were becoming shorted to the motor body or to ground would I suspect the switch as the cause of a circuit breaker trip.

Here is a LIMIT SWITCH TECHNICAL GUIDE [PDF] from Abzil North America https://us.azbil.comhttps://inspectapedia.com/electric/Limit-Switch-Technical-Guide-azbil.com.pdf retrieved 2018/05/09 original source http://us.azbil.com/CP-GC1003E_Vol.1_a_c/D/TEC_LIMIT_SWITCHES.pdf

That document points out a fundamental design criterion: the switch circuit must be configured so that it won't be shorted if the limit switch malfunctions. This ought to be the case for all motor thermal limit switches.

This article from US Motors explains thermal switches on motors in a clear concise page http://acim.nidec.com/motors/usmotors/techdocs/profacts/winding-temp-protection/thermostats

On 2018-05-09 by JJ

Have an ao smith motor new start/run caps centrifugal switch is good windings are good only part left is the thermal limit switch can this part cause house circuit breaker to trip on startup it trys to start 3 seconds or less circuit breaker trips and motor fails to start.

On 2017-08-25 by (mod) -

Patrick,

Please try the diagnostic steps at AIR CONDITIONER WON'T START at https://inspectapedia.com/aircond/Air_Conditioner_Wont_Start.php

and let me know how that works for you

On 2017-08-24 by Patrick

neither the fan to the furnace and ac unit wont turn on the thermostat clicks but nothing turns on

On 2017-07-18 by (mod) - compressor motor is failing

Greg,

I suspect the compressor motor is failing. A service tech can confirm that by current draw measurements.

On 2017-07-17 by Greg

I have a problem with my compressor motor which keeps overheating. It automatically resets itself after 30 minutes or so. I keep the house at 80 during the day and 77 at night. Any ideas on what I need to do? I live in Boca Raton Florida

On 2017-07-09 by (mod) -

Ronald

I can't quite see from my spot what the tech fixed in the air handler: perhaps a fuse or a bad control board relay. When she comes to fix it again I'd look into protecting the wiring in metal conduit since your dog clearly likes the taste of those wires.

Other animals will chew wire insulation too, such as rats (bad dogs), cats, and squirrels.

On 2017-07-09 by Ronald

My dog chewed apart the two wires that run from house to ac unit. Twist back together but fan or compressor will not come on. Fuse was blown on control board and replaced but fan or compressor still doesn't works. Can manually press contact's and everything works.

A technician came and fix it in 10 mins in the attic. Now my dog has done it again in one week. What did the tech do, I have done everything. Is there a reset button somewhere for the fan and compressor inside or outside. This is an old carrier a.c. unit

On 2017-06-12 by (mod) -

Ryan,

Provided you're comfortable and trained enough to not get killed fooling with the electrical components, (no offense intended I just prefer live readers) you'd check for voltage right at each motor's terminals, and if not present work backwards from that point.

On 2017-06-11 by Ryan

AC unit is approximately 10 years old. It quit working and will not turn on. I turn the thermostat to “Cool” and all I hear is a click at the outside unit but nothing goes on, neither the fan nor the compressor. Last summer I was hearing the compressor flutter a bit (like it was struggling) so I think that may be the issue.

I’ve checked the voltage and I have 240v coming from the elec panel and into the disconnect near the unit. I also have 240v going out of the disconnect to the contactor. I checked the incoming voltage at the contactor, also 240v (120v between hot/ground, and 120v between 2nd hot/ground). I replaced the capacitor with a new one this spring.

I also replaced the contactor. The fact that I’m hearing a click leads me to believe that the thermostat is initiating the contactor. I haven’t been successful in ensuring I have 24v across the contactor to the capacitor but the fact that I have a brand new contactor makes me think that’s not the issue.

I did try to bump the fan manually when the entire system was on “Cool” – nothing happened. Inside, I’ve got a new filter and I don’t have a clogged condensate line. This leaves only two things, the fan motor and the compressor. How can I test those two to see which one is the problem?

Seems like one of the two should turn on regardless when the thermostat calls to start the cooling, unless they are both bad?

Or is the fan interlocked with the compressor somehow? My understanding is that the call to cool from the thermostat wire initiates 24v across the contactor to send to the capacitor which then fires the fan and the compressor and the voltage demand is transferred to the permanent electrical wires.
Any help is much appreciated.

On 2017-06-01 by (mod) -

If we assume that you have already checked the obvious such as the thermostat switch settings, then the best diagnostic procedure I can suggest is organized in an article that you can find by using the website search box above. Please look for

LOST COOLING

And let me know if that is successful for you.

On 2017-06-01 by Lil Timmy

The AC Unit does not turn on. ( I don't hear the compressor and fan is not spinning)

Any ideas what that can be? Thank you again!!

On 2017-05-31 20:21:36.301417 by (mod) -

Thermostat not calling for cooling

No power to the fan - a bad control board or relay

A bad fan motor

A bad fan start-run capacitor (this is probably the most-common failure)

On 2017-05-31 19:28:06.541148 by Lil Timmy

My ac condenser fan not turning on? What would be the cause to this?

On 2017-05-27 00:37:39.227934 by (mod) -

Percey:

If a check shows voltage at the fan motor terminals then the motor is shot and needs replacement.

WATCH OUT: turn power off when accessing equipment and watch out for hazards of death by electrical shock.

On 2017-05-26 by percy

I have a heatpump. The fan motor will not come on. It is a Gentec X13 1/2 HP. It does not have a reset switch.

On 2017-05-27 by (mod) re: what to do if the fan motor won't run

Percey:

If a check shows voltage at the fan motor terminals then the motor is shot and needs replacement.

WATCH OUT: turn power off when accessing equipment and watch out for hazards of death by electrical shock.

On 2017-05-26 by percy

I have a heatpump. The fan motor will not come on. It is a Gentec X13 1/2 HP. It does not have a reset switch.

On 2017-04-13 by (mod) re: water pump won't stop running

Sure, Spenc.

By using the search box just above to search InspectApedia for PUMP WON'T STOP RUNNING we find WATER PUMP WONT STOP RUNNING that explains how to diagnose and fix the problem.

It sounds as if your pump is having trouble reaching the cut-off pressure but we don't know if that's because of a low flow well, piping leaks, low voltage to the pump, a damaged pump impeller, etc.

On 2017-04-13 by spenc

cut-in an cut-out reach the proper lbs it takes about 20min to reach the cut-out pressure an by then the pump is extremely hot.....can anyone help me out please

On 2017-01-26 by (mod) re: Signs of an overheating electric motor on an HVAC system

I can't say what's wrong from the information in your question, Fatima. But it might be an overheating or failing motor.

On 2017-01-26 by Fatima

I have a Lennox cooling / heating electric system. It starts working pretty well, but the condenser stops working after 10 minutes working. Why?

I have a Lennox heat/heating system. It starts pretty well, but the condenser stops after 10 minutes working. Why?

On 2017-01-07 by (mod) re: turn off electrical power to a seized motor

Yes, Stephen, that would be the normal case.

I would add that if a motor is seized it would be safest to turn off its electrical power.

On 2017-01-07 by Stephen

We had an ice storm last night and the outdoor moter siezed up. Does the emergency heat bypass the heat pump and just run the fernace? (It's duel fuel tran)

On 2016-01-20 by (mod) re: well pump protector may shut down the pump if water is low

If your system has a well protection circuit or control or switch it may be shutting down the pump to prevent a burn-up of a pump running constantly but unable to find enough water to reach the cutoff pressure.

Then when the pump is off the well slowly recovers so that by day time you can turn it on again and reach cutoff pressure again.

I'd look for
- leaky foot valve

-leak in well piping

- slow well recovery rate

- high current draw at the pump indicating a pump motor failure developing

On 2016-01-20 by Dan

My well shuts off at night. I have to hit the reset button every morning then it is OK for the rest of the day.

On 2016-01-19 by Anonymous re: intertherm blower motor won't start

I think you needed a service tech to confirm power & check relay and control board but first confirm the thermostat is calLing for heat.

On 2016-01-18 by KATHY R.

INTERTHERM BLOWER WON'T START, MOTOR TURNS FREELY,REPLACED CAPACITOR, STILL WON'T START.

On 2015-12-20 by ken walsh

Im contending with a efm motor problem unit modelpk750-4206-2 motor s#316p-393 first I had to restart with reset switch on the pump multiple times it started rite up it shut down again and

then had to start with motor reset switch then shut down again motor reset switch was not triggered hit the pump reset switch and

was getting a buzzing noise took a brick and banged on the motor wile it was buzzing and the unit started rite up is there a low spot in the motor brushes and if the motor is defective what would the retail price be new or used

On 2015-12-12 by (mod) re: reset button on a Trane electric furnace

Ann:

Trane sells heat pumps, gas furnaces, perhaps heat pumps with electric backup heat.

An electric furnace may trip a circuit breaker if the electric heaters are in trouble. Those'd be in the electrical panel.

There may also be local circuit breakers in the unit controlling the heating elements.

If a blower motor won't run there MIGHT be a re-set button on the motor itself.

On 2015-12-12 by ANN

FIND RESET BUTTON ON A 2000 ELECTRIC TRANE FURNACE

On 2015-08-14 by (mod) re: internal thermal overload in electric motor turns it off and back on

The motor may have an internal thermal overload switch that automatically re-sets when the motor cools.

I'm not a motor expert but I'd at least check for

- improper voltage

- improper wiring

- a binding bearing or moving part that is stressing the motor

- missing motor lubrication

- a motor winding that opens up (and stops the motor) when the motor gets hot

On 2015-08-13 by dave.irland@gmail.com

I repowered a direct drive organ blower from the 1920s with a Baldor airover .5 hp 1100 RPM (same specs as original) and made it a belt drive. The motor shuts off after about an hour, very hot to the touch. The motor does not have a thermal overload switch (Baldor CHC365A) but it will re-start when it cools off.

Question 1: if it doesn't have an overload switch, what is happening?

Question 2: (this is where it gets weird)

The motor is on a switched duplex outlet. I have a small fan plugged into the other receptacle to cool the motor.

When the motor switches off, the small fan also stops (??). AFter five minutes the small fan will come on again, run for a few minutes and then shut off; the motor does not come on until the small fan has started and stopped a few times.

I can only surmise that the circuit in the church has some sort of automatic overload switch?? It does not trip a breaker.
thanks

On 2015-07-06 by (mod) re: signs of a seizing AC compressor

Sounds like a seizing compressor motor drawing high current. Leave it OFF while waiting for a repair, lest you have a fire or cause further equipment damage.

On 2015-07-06 by Sal

Condenser sounds like it wants to start and does not. You can see the power drain on the lights as it tries to start up. Any thoughts on what might be causing this?

On 2015-04-08 by (mod) re: how to get help with a mobile home where nothing is to code

Robin

You might give a call to your local building department (or hire a private home inspector) for help in setting repair priorities.

On 2015-04-04 by robin Monterastelli

great site ... also does you company help in CA? my Mobile home is 1964 NOT ONE THING is TO CODE...
I NEED HELP

On 2015-03-11 by (mod) re: table saw motor quit running

Sure Bruce; and easy to test = if you're able to disassemble and rebuild a motor, probably you're up to testing the switch for continuity.

An alternative is more subtle: an open winding in the motor.

See ELECTRIC MOTOR WON'T START in ARTICLE INDEX .

On 2015-03-10 by Bruce s

my table saw motor quit. I took it apart and cleaned everything brushes look good , fan is clear, no spin drag or interruption bearings seem to be in tact . could it be the reset switch? it is located on outside of saw cabinet

On 2015-03-03 by (mod) re: furnace motor always runs

Sorry Nick I don't understand the situation from just your e-text but I can hear that it'd be appropriate to call-back the service person who did the motor replacement to check on wiring and control connections.

On 2015-02-28 by Nick

Hi, my motor in the furnace was changed and now it always runs, also my thermo pump does not go on. Can you help.

...

Continue reading  at ELECTRIC MOTOR OVERLOAD RESET - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• CAPACITORS for HARD STARTING MOTORS for advice on adding or replacing a start/run capacitor for an electric motor that has trouble starting.
• ELECTRIC MOTOR DIAGNOSTIC GUIDE
• ELECTRIC MOTOR WIRING DIAGRAMS & GUIDES

Suggested citation for this web page

ELECTRIC MOTOR OVERLOAD RESET FAQs-2 at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to ELECTRICAL INSPECTION & TESTING

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