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  1. #1
    Join Date
    Aug 2012
    Location
    Los Angeles
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    18

    Trane RTU IDFM keeps running?

    Morning guys, Trane package unit had me scratching my head.
    Trane 3ton RTU YCD036C4LOBE manufactured 1/2001

    Symptoms: IDFM keeps running, T-stat NOT calling for heat/cooling/fan

    Trouble shoot: Identical unit on the roof so I swapped out t-stat, control module, ignition module, inclosed IDFM contacter, removed spade connector to the high limit inside the heat exchanger and IDFM compartment.

    Any Ideas?

  2. #2
    Join Date
    Oct 2011
    Location
    Chicagoland Area
    Posts
    4,681
    Common problem. Windings are shorted.
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    I know enough to know, I don't know enough
    Liberalism-Ideas so good they mandate them

  3. #3
    Join Date
    Aug 2012
    Location
    Los Angeles
    Posts
    18
    really??? when the IDFM contactor is de-energized by manually removing 24v leg, motor stops running.
    In other words IDFM contactor is constantly energized.

  4. #4
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    18,790
    Get pro status and ask in Pro Commercial. We can tell you all about it.

  5. #5
    Join Date
    Aug 2012
    Location
    Los Angeles
    Posts
    18
    Trying to get there, few more posts to go.

  6. #6
    Well the contactor can only be energized from a few sources. Either the secondary limit (TCO2) is energizing it; in which case the switch is either overheated or stuck; or the economiser is calling for fan for some reason, or the fan delay relay is stuck or incorrectly energized. I would bypass the economizer to rule it out and then see where your IDF contactor is getting energized from by checking for voltage through your TCO2 and FDR from terminals 1 and 2.

  7. #7
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    18,790
    Quote Originally Posted by TheDecline View Post
    Well the contactor can only be energized from a few sources. Either the secondary limit (TCO2) is energizing it; in which case the switch is either overheated or stuck; or the economiser is calling for fan for some reason, or the fan delay relay is stuck or incorrectly energized. I would bypass the economizer to rule it out and then see where your IDF contactor is getting energized from by checking for voltage through your TCO2 and FDR from terminals 1 and 2.
    That's not the issue, but I don't discuss the tech stuff in the open forums.

  8. #8
    Join Date
    Aug 2012
    Location
    Los Angeles
    Posts
    18
    Will try that and get back to you guys

  9. #9
    Join Date
    Oct 2011
    Location
    Chicagoland Area
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    4,681
    IDF is indoor fan or induced draft fan???
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    I know enough to know, I don't know enough
    Liberalism-Ideas so good they mandate them

  10. #10
    Join Date
    Aug 2012
    Location
    Los Angeles
    Posts
    18
    Idfm, indoor fan motor

  11. #11
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    18,790
    Well my bad then. I thought that stood for induced draft fan motor in your post.

  12. #12
    Join Date
    Oct 2011
    Location
    Chicagoland Area
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    4,681
    Mine too.
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    I know enough to know, I don't know enough
    Liberalism-Ideas so good they mandate them

  13. #13
    Join Date
    Jul 2001
    Location
    maryland
    Posts
    1,355
    is it on EMS?
    Saving the world...one service call at a time.

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