Blower turned off/element(s) didn't!

Questions about repairs and parts for Coleman furnaces, air conditioners and heat pumps for manufactured homes. Click here for Coleman parts.

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katzdad
Posts: 10
Joined: Sat Oct 24, 2009 4:27 pm

Hi,

I have a Coleman Presidential, model 6806, 240 vlt electric furnace in my mobile home. The last two times I used it on a thermostat, when it reached the correct temperature, the blower turned off but the elements (or at least one element) did not. It got so hot it smelled, and set off my smoke alarm. The front surface of the furnace was very hot to the touch. Both times, I immediately shut off the breaker at my circuit breaker box. Since then, I've wired the ends of the thermostat wire together and operated the furnace from my circuit breaker box. Obviously, this is a serious problem. I have checked the entire unit for loose wires, crossed wires or connections, etc., but found nothing obvious. Can you tell me which part in the furnace I need to replace, so that the elements will shut off when the blower does?

Also, I noted on your parts web page that you sell a 'limit switch' that will shut off the element if the furnace overheats. I would like to use one or more of these, even if I fix the shut-off problem...do I need one for each element (I have three elements)? The part number on my current limit switches is L150-3.5, however, it looks exactly like your part number 3400-3151(L175-50). In addition, on your above mentioned safety limit switch, I do not see how to mount it, since my three are mounted through the flange.

Thanks,
Max
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Robert
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Location: Tennessee

Hi Max,

Will need the complete furnace model number, 6806-?????? to see if I can help.



Thanks,
Robert
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katzdad
Posts: 10
Joined: Sat Oct 24, 2009 4:27 pm

The number is 6806-732. I believe it came with the trailer, which was manufactured in 1971.

Thanks,

Max
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Robert
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Location: Tennessee

Hi Max,

Look at the 6806-732 thread from yesterday and read my last reply to Jake.


That is exact same answer and most likely problem and fix for yours.


Will need same info.



Thanks,
Robert
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katzdad
Posts: 10
Joined: Sat Oct 24, 2009 4:27 pm

O.K., I'll pull mine out and see what the number is and order a new one.

Meanwhile, wouldn't I be well served to put in a new Limit Switch that has the safety turn-off if the temperature gets too high? I'm looking at the model L39-241 Limit Switch. Do mounting instructions come with it? My limit switches have flanges, through which two screws connect it to the plate. Also, will one L39-241 Limit Switch service all three elements, or do I need to get one for each element?

Thanks mucho!

Max
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Robert
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Location: Tennessee

Hi Max,

Get me the info on the KW rating for your furnace and each element coil and how many coils you have.


Will also need to know the numbers off of all the limit(s) your furnace currently has.


Do not order anything just yet as all this will have to be correct and as closely matched as possible for safety.

You will need new sequencers and limits for this to work .


Thanks,
Robert
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katzdad
Posts: 10
Joined: Sat Oct 24, 2009 4:27 pm

Would all the info you need be on the wiring diagram for the furnace? If so, can I take pictures and post them here, or send them to you? Then you can tell me exactly what to order. Keep in mind that I definitely want to get the Limit thingies that will shut down the elements if the furnace gets too hot. If necessary, I'll be glad to order and install a separate unit for that. Like most older mobile homes, mine is a firetrap...aside from the little bit of insulation within the furnace itself, mine is surrounded by very dry paneling. Had I not been at home and heard the smoke alarm (one of which is mounted on the ceiling directly in front of the furnace), I'm sure it would have caught fire...it was that hot.

Thanks,
Max
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Robert
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Location: Tennessee

Hi Max,

It would be on the data sticker or nameplate for the furnace. We have recently moved, I will ride back over to old home tomorrow or Thursday and get my old Nordyne service book and look it up if you do not have the info.


Thanks,
Robert
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katzdad
Posts: 10
Joined: Sat Oct 24, 2009 4:27 pm

I just downloaded the service manual, which includes the parts numbers, KW, etc. Will go through it tonight and get the relevant info and post it. Thanks again for all your help!
Max
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Robert
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Hi Max,

You're very welcome, happy to help.



Thanks,
Robert
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katzdad
Posts: 10
Joined: Sat Oct 24, 2009 4:27 pm

O.K., here's what we've got...

Coleman Presidential
Model 6806-732
3 elements
15KW

According to the Coleman manual, the Sequencer part number is 6806-3321. It's a four post sequencer. Your part number 6806-3631 is supposed to be the replacement for it, but it looks different. Does that matter? Mine has all four posts on top, facing me after I take off the cover. Yours has two on top and one on each side.

According to the Coleman manual, the Limit Switch(es) part number is 6806-3351 (on the Limit Switches themselves, mine say L150-3.5 6806-335, without the 1). You have a part number 6806-3351 (which is supposed to replace mine), HOWEVER, that's a part for a gas furnace. It does look the same shape as my three, but can't be right, I don't think. My part has the following writing on it...20601L65-663 FIV. Is it possible the wrong Limit Switches were at some time installed?

If you need more information, please let me know.

Max
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Robert
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Hi Max,

Been a hectic day, so just getting a chance to answer questions. Will look all over and reply back later tonight or tomorrow.


Thanks,
Robert
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Robert
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Location: Tennessee

Hi Max,

Sequencer # 6806-3631 is correct. Your furnace will need two of them however. The top two A spade terminals are in and out to first element and the blower motor.

The middle M sides are in and out to the second element.


The top two A spades from second sequencer are in and out to the third element.


The bottom H spades on both are for the low voltage from t-stat to energize them.


Limit # 6806-3351 is correct limit, you will need three of them.


A lot of limits are used in gas and electric furnaces, they detect overheat and shut down low voltage circuits in both, so they do same job in either one.


They can be seen and ordered through PayPal from this page here :

http://www.mobilehomerepair.com/ColemanElec.html


The sequencers are pricey, but are the designated ones for your furnace.


Shipping is $8.00 .


Thanks,
Robert
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katzdad
Posts: 10
Joined: Sat Oct 24, 2009 4:27 pm

Robert,

Well, here's with the continuing saga. I have uploaded pictures to possibly help.

My unit has three sequencers. Two are four pole, and one is six poles, HOWEVER, the one with six poles is only connected on four of the poles...H1/H2 and M1/M2. (I've included a picture of the six-pole sequencer, and the figure from my manual, as I can't find a replacement number for it on your web site.)

I decided to test the sequencer connections, per my newly acquired Coleman manual.

I made sure the circuit breaker was turned off, then tested all sequencers. All H1/H2 poles had continuity, and all M1/M2 poles did not. On all three sequencers. On the six-pole sequencer, even though they were not connected to anything, I also test A1 and A2, and there was no continuity.

I reconnected the wires, then turned on the unit from the thermostat end (actually, it's disconnected from the thermostat, so I twisted the two wires together.) After a short pause, it came on.

I tested the voltage at both ends of the heater elements connections (where the black and red wires connect to the elements, on opposite sides of the unit), and got about 120 volts for each connection.

I then turned it off by untwisting the two thermostat wires. The blower went off, but I could still hear a humming sound from the heater.

I then tested the heater elements connections again, and they still had 120 volts...both on the black wire ends and the red wire ends. This indicates to me that they were still 'hot.' I waited five minutes, then tested them again, and they were still all 'hot.'

I next turned off the unit at the circuit breaker, and pulled the Limit Switches. I pushed in on element side face, and one felt much different than the others. It never made the 'click' type movement the others did.

I surmise the following: for some time before I had the dangerous overheat problem, the unit has been 'on,' and has been turning the power to the elements off and on again through the Limit Switches. One finally wore out, and that's when my unit got so hot. It may have been that way for years, as far as I know. Or I may be completely wrong about all of the above.

Please advise. If I need three new sequencers, that's fine. The price is not the problem...fixing the thing so it doesn't burn down my mobile home is. (BTW: regardless of how this turns out, I'm installing a single head fire sprinkler system in the area above the furnace. I'd rather deal with water damage than two incinerated cats.)

Thanks,

Max
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Robert
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Hi Max,

As years pass, the parts arrangements do to. The sequencer I listed is what is designed/recommended for your furnace toady.

You will need 2 of them and 3 of the limits.

ALL of the H spades on your current sequencers are your low voltage (24vac) connections from t-stat.

ALL the M and A spades are the element connections.

The new sequencers will be A on top and M on middle spades and H on very bottom.

Wire it as I previously stated.


Thanks,
Robert
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