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  1. #1
    Join Date
    Jul 2007
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    New Jersey
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    3,031

    inducer motor fault

    can an inducer switch fault and rollout switch fault cause a fuse to blow. LED shows 6 and 7 flashes on carrier rooftop. gas heat. Fuses blew yesterday, today 1 blew. I followed wires back from fuses,( not main disconnect fuses, the 3amp fuses from primary of trans former) going to inducer motor. I start up unit, and jump r to w to test, motor doesnt start but LED shows the 2 faults. If there faults ok, but why would the fuses blow. Would these be related, I started up in cool mode and all was good.
    “If I have seen further than others, it is by standing upon the shoulders of giants.” ~ Sir Isaac Newton


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  2. #2
    Join Date
    Feb 2006
    Location
    indiana
    Posts
    77
    control circuit in heat mode shorting to ground. keep looking

  3. #3
    Join Date
    Feb 2006
    Location
    indiana
    Posts
    77
    could also be in the board circuit

  4. #4
    Join Date
    Feb 2010
    Location
    butler pa
    Posts
    1,072
    if the switch faults to ground it would blow fuse...
    see if any of your wiring to safties are rubbing at a panel etc...

  5. #5
    Join Date
    Jan 2010
    Posts
    5,812
    Whats the unit model # ? Buy the little popper instead of more fuses to find your problem.Did you replace the motor ? or test ?

  6. #6
    Join Date
    Jul 2007
    Location
    New Jersey
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    3,031
    Quote Originally Posted by VTP99 View Post
    Whats the unit model # ? Buy the little popper instead of more fuses to find your problem.Did you replace the motor ? or test ?
    No not yet. just jumped r to W1 to test heat circuit. No trips, just board flashing codes. Model # 48TJD020, series # 670YA, serial 3199F38806
    “If I have seen further than others, it is by standing upon the shoulders of giants.” ~ Sir Isaac Newton


    I'm learning all the time, the tombstone will be my diploma!!!


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  7. #7
    Join Date
    Nov 2006
    Location
    Southeastern Pa
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    17,011
    I'm curious. All of the Carrier units like this that I have seen have a little breaker over by the terminal strip, and one five amp blade fuse on the ignition board. Is that what you have?

    Usually, the switches you mentioned do NOT cause an overcurrrent condition. When I have a code for a rollout fault, I shut off the power and disconnect one lead, and read resistance across the switch. A good switch is usually less than one ohm from terminal to terminal, and a new switch is less than .3 ohms.

    Unless the board is smoked, you probably have a short to ground somewhere. Even a shorted wire in the economizer section will blow a fuse, even with no call for cooling.

    Now, one more thing. There is a chronic problem with posts left on the board without an ending, so, if you would, please post back here with the resolution you found. Thanks.

    And ask for more help if you need it.
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  8. #8
    Join Date
    Sep 2006
    Location
    Ohio
    Posts
    441
    Quote Originally Posted by Tommy1010 View Post
    can an inducer switch fault and rollout switch fault cause a fuse to blow. LED shows 6 and 7 flashes on carrier rooftop. gas heat. Fuses blew yesterday, today 1 blew. I followed wires back from fuses,( not main disconnect fuses, the 3amp fuses from primary of trans former) going to inducer motor. I start up unit, and jump r to w to test, motor doesnt start but LED shows the 2 faults. If there faults ok, but why would the fuses blow. Would these be related, I started up in cool mode and all was good.
    Check the inducer motor windings, if they are ok, it could be the ignition board.

  9. #9
    Join Date
    Jul 2007
    Location
    New Jersey
    Posts
    3,031
    I dont have one 5A fuse, i have 2 - 3.5A fuses. At first both fuses were blown, changed'em to see what would happen and all was ok. Next day same complaint (no power at tstat). This time only one fuse was blown. I traced the wires, they go back to the inducer motor. When a short blows a fuse, would it fry the switches and/or even the board? Like I said originally, when I jumped r-w to energize heat mode, nothing tripped. Thats when it read the 6-7 flash fault codes. In cool mode unit ran with no faults. Im on hold with Carrier now waiting to see what they say.
    “If I have seen further than others, it is by standing upon the shoulders of giants.” ~ Sir Isaac Newton


    I'm learning all the time, the tombstone will be my diploma!!!


    Did you ever stop to think, and forget to start again?

  10. #10
    Join Date
    Jul 2007
    Location
    New Jersey
    Posts
    3,031
    Came in this morning, and Carrier was supposed to fax a hard copy of how to test the circuit board. NO FAX. Anybody know the process for this? Im gonna call again. But in the mean time....
    “If I have seen further than others, it is by standing upon the shoulders of giants.” ~ Sir Isaac Newton


    I'm learning all the time, the tombstone will be my diploma!!!


    Did you ever stop to think, and forget to start again?

  11. #11
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    17,011
    I'll see if I can look this up tonight.

    Sounds unusual for a 48TJ.

    Which wires did you trace to the inducer? Could you give me more specifics?
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

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  12. #12
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    1,747
    Does this unit have the hall effects sensor in the inducer? I have had a couple of these short, when they do they take out the fuse on the board but not before they take out the gas valve. The sensor has 3 wires, red, black, and white if I remember right that plug into the board. I had a e-mail from carrier on how to test but can't find it right now. If I locate I will pass it on.

    good luck.

  13. #13
    Join Date
    Jan 2010
    Posts
    5,812
    Tommy
    Yes your unit has a hall effects in the motor. Three wires go to board from motor as kls says. I'm checking now the wiring diagram on that Carrier unit. Shows 5A fuse on board & 3.2A c.b. going to that fuse. Fuse #1 Black wire feeds primary on trans & L1 at top of board. L1 is relay for motor. Fuse #2 Yellow wire feeds common on trans & common for motor these are high voltage fuses. Still digging hang on.
    Only low voltage fuses i see are the 3.2A feeding board and 5A on board.

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