Old Furnace Keeps Tripping Circuit Breaker Can't Turn On Power


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Old 09-13-14, 01:57 PM
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Exclamation Old Furnace Keeps Tripping Circuit Breaker Can't Turn On Power

I have an old Montgomery Ward furnace ... I have no clue how old it is. It has been serviced about two or three years ago. Most of the parts were changed in an overhaul back in 2009 I think. The model number is AN-6262 Serial number: 06X-E. I wasn't getting any heat so I took a look at the furnace and found the pilot light was out ... I re-lit it, but I still didn't get any heat. Then I found the circuit breaker was tripped ... I reset it and it tripped right away. I turned off the power switch on the furnace reset the breaker, flipped the power switch on the furnace and it tripped the breaker again. A guy on youtube told me it sounded like the blower is shot ... That it was drawing too much current ... without being able to get power to the furnace is there a way I could tell for sure the blower is bad? Anyone have any idea how old this furnace is? The guy that did the overhaul stated it was build like a tank.
 
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Old 09-13-14, 02:55 PM
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Yes, you could OHM out the motor. My guess it's over 25 years old. Just a guess.
 
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Old 09-13-14, 04:03 PM
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You'll have to ohm out all the high voltage parts to find the problem.

Check all connections too; a missing marett could cause a short to ground.
 
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Old 09-13-14, 04:37 PM
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Back in the 70's.... Montgomery Wards furnaces were built by Rheem. Your serial number appears incomplete and the closest I can come is 1970-1975.

I would hope with the age that you've had the heat exchanger checked for cracking and excessive rust.
 
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Old 09-15-14, 07:40 AM
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Arrow Ohm?

Could you explain what need to be done to OHM out the motor? The serial number was what I saw on the information plate ... what is a marett?
 
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Old 09-15-14, 08:04 AM
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A marett is another name for a wire nut.

If you turned your power switch on and the heat started and then the blower tried to start and then the circuit tripped.... I'd say it was the blower motor but the blower motor does not turn on when the service switch is turned on.... therefore it is probably not the blower motor.

You will new a volt ohmmeter set to ohms to look for shorts.
Places to look for shorts.....
1) inside the service switch.
2) inside the junction box inside the furnace.
3) inside the fan/limit control usually mounted in the plenum just above the burner.
 
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Old 09-15-14, 05:27 PM
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Arrow Okay Correct Me If I Am Wrong

So when I use my Ohm meter ... if I get a zero reading that means there is no short and if it goes to infinity that means it has a short?
 
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Old 09-15-14, 05:46 PM
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When you test continuity with an ohmmeter.... always make sure there is no live power or your meter could fry.

If you are using an analog meter.... set it to Rx1. Touch the leads together and set the meter to 0 ohms. If you are using a digital meter... just set to auto. When you touch the leads together with either meter the display would show you 0 ohms which is considered a dead short. So you need to identify 0 ohms. As you check thru your electrical connections you'll find varied readings. If you were to check the motor you may see 10-20 ohms. The control board may check at 50 ohms, etc. When you find something that causes the meter to read 0..... that would be your culprit. Look for the 120vac to 24vac transformer.... those have been known to dead short.

Your 120v enters thru a service switch and then goes into a junction box inside the furnace. You may need to open that junction box and trace the incoming black hot wire to where it splits. You need to split apart the wires and check each one.

Normally I could tell you exactly what to check but I can't find any info on your furnace. You could take a few pictures of the inside that we can use as a guide.
 
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Old 10-02-14, 11:08 AM
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Arrow Okay ... I'm Back

Had another issue I had to deal with, but I am going over what you said to see if I can come up with something ... but I'm really not seeing what I should be measuring so I put up these pictures of all the electrical and mechanical parts in the hopes that will help to tell me what and how to check with my digital multi meter The first picture is the on off switch ... as soon as I turn that on the circuit trips Next is the unit the power switch and fan switch goes to ... the next two are the motor and the drum, the last is the fan
 
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Old 10-02-14, 11:11 AM
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Arrow Another picture

Thought I put up a picture showing where the two wires lead from the one box ...
 
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Old 10-02-14, 11:28 AM
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I've hijacked your picture. The red arrow is pointing to a possibly shorted location. That metal jacket of that MC cable has fallen out of an incorrect connector.

Your next step would be to open that junction box and look for missing wirenuts.
If no missing wirenuts.... then it will be time to open the splices inside that junction box. You should find three black wires connected together and three white wires connected together. Separate the wires and check each pair from black to white for dead shorts.


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Old 10-03-14, 09:49 AM
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Arrow Possible problem part

Well I tighten up that part that was loose and covered the wires, and for a minute I was able to turn it on with out the circuit breaker tripping ... it was about to come on then it trip the circuit. That makes me wonder if this part in the picture isn't the problem? I have a shot of the wires and I took a shot of the off on switch, but it look ok. Seeing how the furnace almost came on could that part be the problem ... how should I check it with my digital meter? What is that part anyway and how would I go about finding a replacement?
 
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Old 10-03-14, 10:28 AM
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With due respect, that's a very old furnace and I think you're in over your head. If you want to keep it running, call a pro to thoroughly inspect the heat exchanger and find the short.
 
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Old 10-03-14, 02:22 PM
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I disagree ... it was fully inspected a few years ago ... and there are only so many electrical components... I don't have the funding for a "pro". I'm on my own.
 
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Old 10-03-14, 04:30 PM
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I've removed a couple of un-needed pics to shorten this thread down.

The wiring in your switchbox is ok. Look at the arrow.... if that metal jacket is sharp..... on either end.... it will cause a short.
The metallic cable that connects that box to the furnace is called MC lite and is aluminum jacketed. It should be installed with the correct connectors that don't squeeze the jacket when tightened. I've inserted the pic of a proper connector.

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You took some beautiful pictures of the splice box but I can't quite see all the splices. You have a three wire MC cable feeding that box. I see three white wires.... neutral coming in, neutral to the transformer and neutral to the furnace. I see the black/hot wire coming in from the MC cable connecting to the black of the transformer and ??

You need to open those two connections up. Use your meter to check the incoming MC cable (white to black), the transformer(white to black) and the two wires to the furnace. The transformer will show continuity but it should not be a dead short.
 
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Old 10-03-14, 04:42 PM
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So when I use my Ohm meter ... if I get a zero reading that means there is no short and if it goes to infinity that means it has a short?
In general, that is completely wrong and opposite of being correct. Knowing where you are measuring from and to would help.
 
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Old 10-03-14, 04:51 PM
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Your pix show an electrical rat's nest. Call in a qualified electrician to sort things out. If you can't afford one, than we can't really advise you. If you were my neighbor, I would come over to help, but I'm not.
 
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Old 10-03-14, 07:51 PM
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[quote]I disagree ... it was fully inspected a few years ago ... and there are only so many electrical components... I don't have the funding for a "pro". I'm on my own.
[/quotes]

Needs to be checked at least every year at that age.
 
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Old 10-03-14, 08:07 PM
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I will check that out, but what about the other part inside the furnace in the one picture ... what is that part what does it do and what would I have to do to find a replacement part if bad ... that part seem to have an affect when I tried to tighten the screws holding it. There is only one screw that fits to hold that piece I don't know why that is ... but am I wrong to suspect that part?
 
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Old 10-03-14, 08:45 PM
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Are you talking about the connector that holds the wire into the box.
If yes.... did you read my last post ?

That is an incorrect connector for that type of wire. That is a non metallic cable connector. You need an MC - metal clad connector like I posted.
 
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Old 10-03-14, 11:34 PM
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Arrow No ... this part ...

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No I mean the part in this picture hanging down with the yellow and red wire attached to it ... the one that I tried to tighten and the furnace almost worked after doing so ... could this be the bad part ... what is it? How do I go about checking it to see if it needs to be replaced ...
 
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Old 10-04-14, 12:52 AM
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Disconnect the white and black leads on the back and check them for continuity.
I explained this back in post 15.
 
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Old 10-06-14, 05:10 PM
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Arrow Found it ... but more trouble ...

A friend of mine has a son that is good with electric so he checked out my furnace and found that there was continuity between the wires and the furnace which indicated a ground to short ... after searching around he found it in the on/off switch box and that stop the fuse from tripping ... however when it fired up we got a light show from the motor which indicates the bushing are going ... can any one help me find a replacement part ... the picture shows all the info on the motor. Hopefully it is clear enough ... and the thermal coupling needs to be replaced, but that should be no problem. So if someone can set me on the right track to finding a replacement please post.

For now ... I have heat
 
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Old 10-06-14, 05:25 PM
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Arrow Posting numbers ...

I blew up the photo so I could see the numbers ..
HR: 1/6
FR: 48
Mod: 5KH33GG111EX
RPM: 1725
SF: 1.35
V: 115
A: 3.4
Time Rating: CONT
Ser.NO.: WSA
 
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Old 10-07-14, 08:41 AM
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If he found the short in the switch box - it was where my arrow was pointing back up in post 15.
 
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Old 10-08-14, 08:59 AM
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Arrow Need help finding a replacement AC motor.

That is correct
Now is there any one that can help me find a replacement part?
 
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Old 10-08-14, 09:22 AM
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Old 10-08-14, 11:26 AM
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Arrow How did you find that????

Wow ... you am a genius I checked ebay and didn't see this ... Thank you. But I am wondering about the wires ... I don't see anything for that ... check out the picture of my motor ... I'll contact the seller and find out for sure ... I which I knew how to draw arrows in the picture ... but you see the connector on top ...That is what concerns me. The wires go directly into the motor ... there is no way to remove them to my knowledge ...
 
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Old 10-08-14, 11:38 AM
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I rotated the motor listed on ebay in the same orientation as yours. It appears there is a "knockout" in the motor exactly where your motor has the wires entering.
 
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Old 10-08-14, 01:08 PM
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In the picture.... the red line is the motor wiring plate which is held on with two screws(white).

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Old 10-08-14, 03:47 PM
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How do you add those arrows to the picture? I'm not sure how to get inside the casing ...haven't taken a good look at it yet, but I will check it out ... I wrote to the seller on ebay for more info on that part and sent a picture of my old motor.
 
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Old 10-08-14, 05:14 PM
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That's why I drew the red line and the arrow. That IS a cover plate with two screws that you take off to access the wiring.

I use the paint program in windows. You right click on a picture and then select "open with paint." Once in paint there are all kinds of things you can do. Take an extra picture and go in and experiment. When you close the program you can select "don't save changes" and your picture will be unchanged. Select "save" if you want the changes you made to stay.
 
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Old 10-09-14, 09:44 AM
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Fantastic ... I will be out only 65+ bucks ... that will be a help since I have a very limited budget.
 
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Old 11-10-14, 08:25 PM
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Arrow Need info on installing motor

Well sir .... I've had major surgery last month and am still recuperating. I was unable to lift the motor. Now I am at the point where I can lift the motor and would like some pointers on installing it since I've never done anything like this. Is it pretty much cut and dry? Shut off the power and remove the wires and un mount the motor then the opposite to install? What do I need to watch out for? Does it look like it will be difficult to install? Even though the blower is no longer working I am still getting heat. Will that cause a problem with the blower out?
 
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Old 11-12-14, 07:03 AM
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Arrow Still wondering

Does anyone know whether or not running the funance without the blower is harmful? Also is all I have to do to change the motor is turn off the power?
 
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Old 11-12-14, 04:06 PM
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Running the furnace without the blower can do major damage to the furnace. Turn off the power at the service switch (external to the furnace) or at the breaker. Check with a volt meter before touching any wires.
Two things to pay particular attention to are: Direction of rotation & belt tension. If the motor turns the wrong way, the fan won't move air as it should. If the belt is too tight, you will soon burn out the motor.
 
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Old 11-13-14, 09:23 PM
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Arrow Will a box fan help?

If it's the same motor shouldn't it turn the same way ... right now I have a fan going to cover for the blower until I can get the motor installed. What kind of serious damage are you talking about? Should I lower the temperature ... I have it set at 70.
 
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Old 11-14-14, 04:46 PM
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It should turn the same direction but might be reversible. Just a heads up.
Running the furnace without a fan could cause the heat exchanger to overheat & fail.

A furnace is on or off. The thermostat is a switch, open or closed. Setting to a lower temp will cause the furnace to run less.
 
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Old 11-18-14, 12:51 PM
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Red face Finally Got It Together Problem Solved!!!! :)

Well sir ... It got pretty cold out side and the furnace wasn't keeping the house warm ... it was suppose to get warm over the weekend and I was planning to replace the motor then, but it looked like I had no choice. I was working blind because I never did this before.

I turned off the furnace at the switch, dropped the thermostat below room temp. I ran into things that slowed me down like removing the pulley.

That was a matter of using a hex wrench to remove the screws holding the pulley. Once those were removed, the pulley slipped right off ... I had to tap the pulley down with a hammer on the replacement motor. I made sure the flat parts match up on the rod. Put the screws back in and the pulley was installed.

In order to get to the wires inside the motor I had to remove the plate on the back with the info on it nearest to the wires. Once I removed the plate I could disconnect the wires ... I made sure I hooked up the wires on the replacement as it was on the old motor. Removing the old motor from its mounts was a bit slow, but I manage to figure it out.

Was a bit awkward putting things back together but it is now running properly and pushing out warm air.

A very warm thanks to all that took the time to post.
 
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Old 11-18-14, 01:40 PM
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You're more than welcome. Helping folks do things right & saving them money is why we are here.
Replacing your first blower motor can be a challenge but it seems you were up to the task.
 
 

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