Testing for bad sequencer on Coleman Electric

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My Coleman EB15B furnace has been operating normally for 7 years. This past week that changed. We run the temperature at 70 degrees. The furnace cycles normally for a while then, just quits. Meaning the fan does not cycle in automatic. I'll run the fan in manual for about an hour then set it back to auto and it will run normally for awhile again. I can hear the electric cycling at the furnace and a hum like the fan will come on, but it doesn't. Again, I'll set fan to manual for about an hour, then return to auto and it will again cycle normally. Any help please.
Thank you in advance.

Mike
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Joined: Sun Feb 18, 2007 3:24 pm

With T-Stat in Heating / AUTO Mode, your Sequencer controls your Blower Motor.

When you change T-Stat to Heating / ON Mode, the Blower Relay controls the Blower Motor.

Usually when this happens, it is either a Sequencer contact not holding, Blower Relay contacts that circuit goes through opening or the T-Stat contacts for Fan control not holding.

To know for sure, you would need a Multi-Meter to test voltages. Do you have one and familiar with the use of it ?

Take care and best wishes,
Robert
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Do not have Multi-Meter tester. Can test be done without? I have a new T-stat, had been planning to replace old lever type with digital.
P.S. it is very warm in furnace compartment. By running fan in manual cooled space a little, then it worked properly.

Mike
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Very doubtful it is the T-Stat. No, you would need a Meter to know which is or is not closing/opening.

With a Meter at time of fault, test across contacts to find the one that is not closed.

Take care and best wishes,
Robert
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Joined: Sun Feb 18, 2007 3:24 pm

What to do when tested which is causing fault? I'll locate a meter tester.

Mike
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You replace the faulty part, which we stock and sell if needed.

Take care and best wishes,
Robert
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Joined: Sun Feb 18, 2007 3:24 pm

Thank you for the help and I'll get back with you after testing.

Mike
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Posts: 1054
Joined: Sun Feb 18, 2007 3:24 pm

Do you know where to test, when to test, the sequence of operation and what you should be testing for ?

I was going to walk you through that step by step when you get the Meter, do you not need that ?

Take care and best wishes,
Robert
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Joined: Sun Feb 18, 2007 3:24 pm

At the Sequencer, test across the bottom brass terminals, H1/H2, H3/H4.

Place one meter lead on each side of Sequencer. One side is H1 and other H2 and so on.

Test for 24-28vac with t-stat set to heat/Auto and calling for furnace to be on.

Then change meter to test for 300+ vac.

Test across top and middle silver terminals, M1/M2, M3/M4 and M5/M6 for 300+ vac.

You should read 24-28 vac at the H terminals and 0vac at the M terminals.

H1/H2 =

H3/H4 =

M1/M2 =

M3/M4 =

M5/M6 =

I edited my old reply above with email address, it was wrong address, sorry about that.

Thanks,
Robert
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H1/H2 =26.37

H3/H4 =26.34

M1/M2 =244.3

M3/M4 =244.3

M5/M6 =no reading


I placed the readings in their respective locations

Thanks Mike
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Posts: 1054
Joined: Sun Feb 18, 2007 3:24 pm

Hi Mike,

Sequencer is bad. With the H terminals reading 24-28vac, the M terminals should be closed and reading 0vac.

With M1/M2 and M3/M4 reading 244.3vac, those sets of contacts are not closing and M1/M2 controls the Blower Motor.

Go to below link for Sequencer info for ordering if interested.

It is Sequencer # 3115-3571 @ $39.99 + $6 shipping.

Click on pic for enlarged view.

To order, please add to cart and order through PayPal or call toll free to 1-877-263-7860 and charge to your Visa or Mastercard.

Thanks,
Robert
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