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Coleman electric furnace won't turn off

12752 Views 5 Replies 3 Participants Last post by  yuri
I have a Coleman Evcon EB15A in my 1993 double wide mobile home. Last winter I replaced the heating elements that came complete with limit switches. I did this because it didn't' seem to be blowing hot air, just luke warm. I replaced the sequencer at that time just for good measure. It blows warm air now. This winter I'm having trouble with the furnace not turning off and heating up the house way above the thermostat setting. I replaced the sequencer again but it continues to do this. I replaced the thermostat. No help. I called the local HVAC guy who said it was the sequencer and replaced it again. In the last three months he has put four sequencers in it and it will work fine for days or weeks but eventually does the same thing and I have to turn off the furnace at the breaker box. He thought the blend-air device was drawing away low voltage from the thermostat so he disconnected it and bypassed it. No help. I can unhook the two wires to the thermostat as they enter the furnace but the furnace still will not shut off. Tapping on the sequencer to "un-stick it" like the tech asked me to do does nothing. He is out of ideas and I've put enough money in this thing to buy a new furnace. Does anyone have any ideas?

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Are you sure you got the right sequencer. How many KW of heat do you have.
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looks like 15 kw from the 15 in the model #. Did U or he check the voltage to the furnace and amps draw of the elements and do you get low voltage conditions? Sounds like it is drawing too much current and arcing/welding the sequencer contacts together. Should not have lower than 220 volts or the amps goes up too high. Rural areas can have voltage problems from overhead wires/pole transformers/raccoons or squirrels chewing wires at the transformer ( yep it does happen, critters short out transformers). If so get the elec co to put a meter clock on their service for 24 hrs and see if the voltage drops during 24hrs. You need to be VERY VERY diplomatic when dealing with them as everyone accuses them of power problems but if you are nice they have a meter clock 24 hr recorder they can put on.
Thanks for the reply. My HVAC guy's only comment this time was maybe he had a bad batch of sequencers. My thoughts are that something is causing this. I live out in the boonies in north Idaho and we have a rural co-op power company and we loose power frequently. They are good people to deal with however so I will approach them with the idea of a recorder and will run this by my HVAC guy.

Thanks again.
Are you sure you got the right sequencer. How many KW of heat do you have.
I replaced the sequencer myself last year and ordered by model number of the furnace. Since then the HVAC guy has put three or four in so I'm not sure. I'm going to show my post and these replys to my furnace guy and hope he does not take offense. He shouldn't. At one point he said he was stumped and then concluded he had a bad batch of sequencers.....
very very rare that you get a bad batch of them and most of them seem to be made by the same TOD company. I suspect a low voltage problem. I had an autobody shop that kept blowing low voltage transformers in a new furnace. Had to get elec co to put a meter clock recorder on after they kept blaming the furnace. low and behold next day I see them climbing the pole and replacing the pole transformer, no problems since.
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