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  1. #1
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    Carrier Rooftop Ignition Faults

    We monitor and control several Carrier 48TJD008-14 with a DDC system and have noticed several lockouts recently. The heating stage 1 signal has been present for days but the supply air does not rise. Turning off the stage 1 heat signal and then restoring it seems to reset the unit. This seems to be a soft fault that can be reset with out resetting the power.

    We won't reset them in the future so that we can have a tech check for fault codes, but until then. Are there any faults that can be reset in this manner?

    The units were manufactured around Jan 2000, and the ignition control board says Automatic Ignition Systems H33WP002A.

  2. #2
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    Yes. When you remove the call, you reset the board.

    A ten year old carrier probably has a bad HX, leading to a rollout switch actuation by flame rollout.

    Other problems typical for the unit include failure of the rollout switch itself, that when it has been actuated a few times, it never fully recovers the ability to close its contacts fully. It is typically not replaced when the HX is replaced, and it should be. The board itself can develop an undifferentiated "internal fault" and it can also show a rollout code when the switch is fine and there is no flame rollout.

    Get your tech out there.

    Get your post count up and apply for pro membership for more specific details in the Pro Technical Forum.
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    2 Tim 3:16-17

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  3. #3
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    I thought most roll outs must be manually reset..he is resting in a soft manner.
    i say we cant see from here to judge...it could be a dirty flame sensor or a dirty initiator..wasp nest in draft inducer..etc etc

  4. #4
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    Quote Originally Posted by yellowirenut View Post
    I thought most roll outs must be manually reset..he is resting in a soft manner.
    i say we cant see from here to judge...it could be a dirty flame sensor or a dirty initiator..wasp nest in draft inducer..etc etc
    The limit in the blower compartment has a manual reset. The rollout does not.
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    2 Tim 3:16-17

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  5. #5
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    just looked in the manual..u are correct. I still say no one can say with certainty what it is.

  6. #6
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    Quote Originally Posted by yellowirenut View Post
    just looked in the manual..u are correct. I still say no one can say with certainty what it is.

    That's right. Only perhaps 90% certainty.








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  7. #7
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    The customer's HVAC tech thinks that all faults have to be reset by a hard reset, but our experience shows that some heating faults must be soft resettable. The documentation that comes with the unit doesn't indicate which. I wondered if there may be other documentation you guys may now of. The manual we have is a catalog # 534-725

    Thanks

  8. #8
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    Quote Originally Posted by timebuilder View Post
    The limit in the blower compartment has a manual reset. The rollout does not.
    I know electric heating unit`s have a manual reset at the top of the blower.On the gas heating you might want to double check the manual reset high limit on the 8 and up unit`s TJ series. When even the rollout is auto reset. When you jump up to a twinned heating section like in the E,F,A,and Z series the roll-out switches are manual reset. But on those larger series the limits are auto reset.
    Last edited by Dallas Duster; 02-12-2010 at 08:43 AM.
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  9. #9
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    Quote Originally Posted by thegoodlistener View Post
    I know electric heating unit`s have a manual reset at the top of the blower.On the gas heating you might want to double check the manual reset high limit on the 8 and up unit`s TM series. When even the rollout is auto reset. When you jump up to a twinned heating section like in the E,F,A,and Z series the roll-out switches are manual reset. But on those larger series the limits are auto reset.
    I wanted to keep this focused on units of that size. I think his tech must be thinking of rollouts of another brand.
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  10. #10
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    Quote Originally Posted by thegoodlistener View Post
    I know electric heating unit`s have a manual reset at the top of the blower.On the gas heating you might want to double check the manual reset high limit on the 8 and up unit`s TJ series. When even the rollout is auto reset. When you jump up to a twinned heating section like in the E,F,A,and Z series the roll-out switches are manual reset. But on those larger series the limits are auto reset.
    There you go I fixed it.
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  11. #11
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    Are these zoned systems? Could just be the wind playing tricks on you. Most alarms can be reset in the manner you are doing, if it's something major it's just gonna trip out again. I always like a 3 strikes and your out policy myself.
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  12. #12
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    It is scary that a fault such as a roll out switch can be reset with out a visual inspection.As was stated before these heat exchangers are famous for rotting out.
    You did not say whether the lock-outs are all on one machine?
    I have even see wasps and flies nest in the regulator vent line (when the screen has rotted out) and cause problems with the heating side.

  13. #13
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    We will check the fault codes the next time it happens.

    Thanks for the replies

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