3400A816 Heating Element Issue

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newdodge4me

Hello Everyone.

This is my first post although I come here often and have found your site very helpful, SO Thanks

My Problems is simple I think, I have a 3400a816 that up until recently was working great. When running heat mode this thing usually runs you out of the trailer from the intense heat that it puts out. All of a sudden its very hard to keep it over 50 deg. when the outside temp is under freezing.

I checked the unit, Heatpump side of things working fine, the electric grids are not firing up (they are set up as 2nd stage, emergency). SOmeone had cut the breaker to the outside condensing unit and the electric was all that was heating for an unknown amount of time so I know they were working fine.

THis is what I have checked.
I first checked Bus Fuses with DVOM, All Good
I then pulled the panels and cut power and ohm'd the coils on the right side as well as the left side. I first checked resistance between the top and center posts (no cont, open circut) I then checked between the center and lower posts (no continuity, open circut) I checked between the top and bottom posts as well just for good measure as I dont have wiring diag so not sure of wiring config of elements and got the same result.
I checked the other sides elements in the same fashion and got the same result. I have open circuts across all posts of the heating elements. By this it is from my experiance that the elements are burnt out?? Am I correct on this?? I didnt check the input voltages as I didnt see the need if I had verified the elements were open.

Now from what I read in other posts in the forums the heating elements are no longer available for this unit. and I need to get restringing kit from the electrical section?? If my diag is correct my question is you offer 3 different kits. this furnace is stamped a 54k BTU. Which kit the 5kw, 3kw?? and how many do I need to restring all of the heating elements??

Should I replace the senquincer?? I know this thing ran for approx a month of continous running on just the electric grids so I am sure they were heated up a good bit.. Thought for the money would it be smart to go ahead and replace it? THis thing has been butchered up by someone in the past so it has been difficult figuring out the info, especially without the electrical diag's But I think I got the basics down. I have installed Heat pumps and done alot of furnace repairs but this one I am just not sure about.. HELP PLEase

I am also wanting to make sure before buying a wiring diag from you. On this unit I really need to know the t-stat panel diag as I cannot see anything on the panel and whoever wired it didnt use normal color codes for the wiring. Will this wiring be included in the wiring diag that you send for the $15 ??

I need to order fast so as soon as you let me know I will get the parts ordered. Its Cold Here on the east coast... :=)
Sincerely
Roger
AKA Newdodge4me :shock:
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Robert
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Posts: 6413
Joined: Wed Feb 28, 2007 12:07 am
Location: Tennessee

Hi Roger,

Can you take a few pics of your element assemblies and send to me at [email protected] ?


Can you also measure opening where front plate mounts and also distance from plate to rear wall of elemnt opening ?


The wiring diagrams are for the furnace and do show t-stat wires with OEM colors.

It does not show where they connect at t-stat though.



Thanks,
Robert
Some people are Humbly Grateful, while some are Grumbly Hateful.................... Which one are you ?
newdodge4me

Thank You Robert, for your fast reply

I have to admit to you that I feel like a idiot. In pulling down the unit I found that I was checking the elements incorrectly(I didnt have the schematics so I wasnt positive)Anyhow to clarify what I have is this. (Pics will be below)
I have rechecked the resistance of the elements and they are all good. I checked the continuity of the overlimit switches and they are all fine. I powered up the unit and cut a request for heat on the unit seting it high enough to trigger the elements as well.
Upon checking I have approx 110v going from the fuse terminal through the limit switches and then into the right side of all 3 elements. I checked and have the approx 110v comming out all 3 sides of the left side of the elements. Each of these wires go to what look like some form of sequencers? There are 2 of them as seen in the pics below. 2 of the wires go to the device on the rights lower pins (red and Yellow wires) And the other yellow goes to the other devices lower pin.

Now I am a certified electrican so the basics state that whatever energizes (grounding the elements) is not working I would think that this is the seqencer??

I have marked each of the voltage reading that were present directly on the picture.

Thanks again for your assistance. I ordered the diag's earlier so they should help once I get them.

Sincerely
Roger

Image
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newdodge4me

I forgot one other thing, I couldnt get a pic of as I would have to unwire have the darn thing to get it, and beleive me with the hatchet job that the previous have done I dont want to do without a wiring schematic.

Anyhow, when testing I get 110vac from the fuses to both sides M1 & M2 of both of the sequencers. M1 comes from the fuse block
and M2 is directly wired to the left side of the elements (on both sequencers)
Of course these are 240vac 5.2 kw elements (from what the sticker says on the element panel that i found when taking apart)

So the when the seqencers energize properly it will allow the 110vac that is on M1 to pass through to M2 and go into the left side of the elements giving them 220vac and allowing them to heat up. They either have to be connected to neutral for 110vac or to another 110vac to allow for 220vac?? Is this correct.. What sends the signal to the sequencer to tell it to energize the elements? Like I said this things wiring has been all hacked up. colors dont match, someone layed a transformer in the unit and hacked it into the wiring. But since everthing worked up intil recently I must assume that the hack job is ok.

Again I thank You for your assistance, as soon as we come up with something I will get over to your order page and get it paid for.

ROger
User avatar
Robert
Moderator
Posts: 6413
Joined: Wed Feb 28, 2007 12:07 am
Location: Tennessee

Hi Roger,

At very bottom is your heater coil terminals. H1 and H2 on one and H3 and H4 on the other.


On a call for heat, you get 24-28vac from H1 to H2 and H3 to H4.

On a NO CALL you get 0vac .


The H numbers are usually listed on a bottom metal plate.



You should have 120vac at M1, M2, M3, M4, M5 and M6 to ground
each with a NO CALL for heat from t-stat.


You should have 0vac ACROSS M1/M2, M3/M4 and M5/M6 WITH a call for heat after 1-2 minutes.



One 120vac leg comes thru limits to right side of elements.


Other 120vac leg stops at M terminals on one side of sequencer.


When the small heater coils get the 24vac and close the M terminals, that other 120vac leg travels to other side of elements.


That gives 240vac to elemnts to use.



Forget the colors, just look at diagram and where each comes from and goes to and wire according to diagram.


Then test.



The sequencers control BOTH the elements and the blower motor is is most likely the problem here.



These aren't rocket science and though they sometimes look like a road map when wired up, take your time and the muddied picture will get real clear.


You basicly need to turn all power to furnace off, get a bright light set up, cut any wire ties or bundles loose and then finger trace each wire one by one.



Take care and best wishes,
Robert
Some people are Humbly Grateful, while some are Grumbly Hateful.................... Which one are you ?
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