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  1. #1
    A FUN TITLE asmo's Avatar
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    Default Need HVAC/Furnace Help - Furnace Dead

    So a few weeks ago I bought a fancy new Ecobee3 thermostat to replace the Honeywell that I had. I hooked it up and everything worked great except the original builder only ran 18-5 between the thermostat and the furnace - so I couldn't hook up the humidifier since I didn't have enough wires (the old Honeywell used a THM5421C EIM to go from 7 wire to 3). So no big deal we went without a humidifier for a few weeks until I could run some 18-10 between the thermostat and the furnace (and humidifier).

    So flash forward to last night. I run some 18-10 between the thermostat and the furnace (no easy task). I hook all the wires up and nothing - furnace wont even power on. I check all my wiring and the safety switch and everything looks good. I test for voltage across C and R at the furnace and I get nothing. I jumper R/W and nothing, I jumper R/G/W and still nothing. I do hear 120AC going into the furnace (hum), but it doesn't translate into anything. I also don't get any lights on the furnace control module.

    Anyone want to help my understand what the hell I am doing wrong. I really hope that the furnace control module didn't puke just because I put some new wires in.

    This is the furnace end before I started:
    Click image for larger version. 

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    This is the furnace end after I replaced the 18-5 with 18-10:
    Click image for larger version. 

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    In both of the above, the top W (going to Y) and the bottom B are going to the safety switch.


    This is the thermostat end (no difference before and after other than different wires -- still the same colors):
    Click image for larger version. 

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    This is the furnace control module (its a RUUD):

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    Any thoughts? I really don't want to have to pay for a Sunday emergency call, but I leave tomorrow and need to have heat in the house before I go.
    Last edited by asmo; 02-21-2016 at 13:17.
    What is my joy if all hands, even the unclean, can reach into it? What is my wisdom, if even the fools can dictate to me? What is my freedom, if all creatures, even the botched and impotent, are my masters? What is my life, if I am but to bow, to agree and to obey?
    -- Ayn Rand, Anthem (Chapter 11)

  2. #2
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    Paging Hghclsswhitetrsh

  3. #3
    I blame everything on Tummy Aches
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    Check voltage going into and leaving the transformer, both 120v and 24v

  4. #4
    Grand Master Know It All
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    You tripped a fuse. Check for a small one on the board or somewhere inside and check the ssu. The transformer might be fried? Hard to tell without real tests. A sound does not mean you have power.

    Get multi meter and learn how to use it before you cost yourself some serious money.

  5. #5
    I blame everything on Tummy Aches
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    Is there anyway possible that you damaged the wiring by pulling the new one, creating a short. I'd start by pulling the wires off both ends and test ohms Red to green, red to yellow, red to blue, red to white red to green. Then green to yellow green to blue green to white etc etc etc.

    Also I didn't see a fuse on the board, is there and I just missed it?

  6. #6
    A FUN TITLE asmo's Avatar
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    Quote Originally Posted by hghclsswhitetrsh View Post
    Check voltage going into and leaving the transformer, both 120v and 24v
    To do that am I going to need to get into the safety switch? I am looking for where I can attach my voltmeter leads to. Is there someplace easy you would recommend.

    Thank you for the help!
    What is my joy if all hands, even the unclean, can reach into it? What is my wisdom, if even the fools can dictate to me? What is my freedom, if all creatures, even the botched and impotent, are my masters? What is my life, if I am but to bow, to agree and to obey?
    -- Ayn Rand, Anthem (Chapter 11)

  7. #7
    I blame everything on Tummy Aches
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    Quote Originally Posted by Wulf202 View Post
    You tripped a fuse. Check for a small one on the board or somewhere inside and check the ssu. The transformer might be fried? Hard to tell without real tests. A sound does not mean you have power.

    Get multi meter and learn how to use it before you cost yourself some serious money.
    Not all furnace control boards have fuses. The SSU fuse wouldn't be tripped from a low voltage short.

  8. #8
    A FUN TITLE asmo's Avatar
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    Quote Originally Posted by Wulf202 View Post
    Get multi meter and learn how to use it before you cost yourself some serious money.
    Does a MS in EE count?
    What is my joy if all hands, even the unclean, can reach into it? What is my wisdom, if even the fools can dictate to me? What is my freedom, if all creatures, even the botched and impotent, are my masters? What is my life, if I am but to bow, to agree and to obey?
    -- Ayn Rand, Anthem (Chapter 11)

  9. #9
    I blame everything on Tummy Aches
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    Quote Originally Posted by asmo View Post
    To do that am I going to need to get into the safety switch? I am looking for where I can attach my voltmeter leads to. Is there someplace easy you would recommend.

    Thank you for the help!
    Are you talking about the door switch? If so then yes, if operating and wires correctly 120 volts cannot get to the board/transformer with out being pressed in.

  10. #10
    A FUN TITLE asmo's Avatar
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    Quote Originally Posted by hghclsswhitetrsh View Post
    Are you talking about the door switch? If so then yes, if operating and wires correctly 120 volts cannot get to the board/transformer with out being pressed in.
    Yup got that part.

    Just looking for a good place to test before the transformer. Everything is sealed up. I'll go back to playing around and see what I can find - good call on measuring the resistance between the pairs.
    What is my joy if all hands, even the unclean, can reach into it? What is my wisdom, if even the fools can dictate to me? What is my freedom, if all creatures, even the botched and impotent, are my masters? What is my life, if I am but to bow, to agree and to obey?
    -- Ayn Rand, Anthem (Chapter 11)

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