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  1. #1
    Join Date
    Apr 2011
    Location
    Chicagoland Area
    Posts
    37

    Trane Intellipak EF problem

    The last couple days the unit has been having an alarm due to the EF not starting (failure). The wiring diagrams are illegible. If you kill power it will start and run fine until the next day. I know its some type of safety, but cannot trace out wiring. The model is a SEHFC554N667A7BD9F1100WE0G0K000RT008000. Any help would be greatly appreciated. Thanks

  2. #2
    Join Date
    May 2004
    Location
    Salt Lake City/Tooele
    Posts
    2,163
    Model shows you should have both VFD for main and exhaust motors? The main contactor/motor start assembly near the exhaust fan VFD, has an auxiliary switch that proves the contactor closed. These have a tendency to flake out, even though contactor is closing and motor is operable the faulty switch is leading the unit to believe the contactor did not close and faulting the system on an Exhaust Fan Failure.

    Should apply for Pro Status...can get you manuals, wiring diagrams, and there are some amazing Ipak guys in those forums, namely Jay.

  3. #3
    Join Date
    Apr 2011
    Location
    Chicagoland Area
    Posts
    37
    Thanks slctech, it does have vfd's for each fan. I'll look into the aux switch and apply for Pro Status.

  4. #4
    Join Date
    Feb 2011
    Location
    richmond, va
    Posts
    20
    If the alarm is exhaust fan failure, the exhaust fan proven switch located on the rtm has open for 40 continuous seconds when ex fan binary output is on, 1u48-j7-13 & 14

  5. #5
    Join Date
    Jan 2002
    Posts
    241
    Like mentioned the DP switch or usually I just bump the minimum HZ up on the VFD.

  6. #6
    Join Date
    Apr 2011
    Location
    Chicagoland Area
    Posts
    37
    Okay everything was fine until two days ago, unit was down again. I bumped up the VFD speed and decreased its accel time to ensure the switch makes within the 40 sec time limit. Today the unit is down again. I have tested the switch with a magnehelic, tried to recreate the problem several times but every time the EF starts and continues running without a glitch. Also have been watching the contactors with aux switches and everything is fine. Any ideas?

  7. #7
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,018
    Quote Originally Posted by 501miller View Post
    ...I bumped up the VFD speed and decreased its accel time to ensure the switch makes within the 40 sec time limit....
    so you SLOWED down the ramp time? i would think that you would have increased it.

    the unit looks at the pressure differential switch to make. this pressure differential switch has a pitot tube on it. the tip of the pitot tube must point directly into the leaving air stream, right off of the exhaust fan. if it is a little off, then you can have issues. and here is how the board works...the board puts out a 24 VDC signal from J7-13 to the switch. the board checks this voltage to the voltage at J7-14. since there is a 24 VDC difference...switch is open. now here comes the fun part, when the switch closes, the 24 VDC goes back to the board, however, the J7-14 terminal is grounded. so, since the 24VDC output is not strong enough to overcome the short to ground, the J7-13 output goes to 0 VDC. the board then compares the J7-13 and 14 terminals and sees no difference, therefore, the switch is closed. they could have made it easy to troubleshoot by not grounding the J7-14 terminal...but they didn't.
    Last edited by jayguy; 03-28-2013 at 10:55 PM.
    It's tube brushing season...93% done (39.35 miles of tubing)...only 1,242 tubes to go!

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    EVERYTHING IS AWESOME!!!

  8. #8
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,018
    Quote Originally Posted by jayguy View Post
    so you SLOWED down the ramp time? i would think that you would have increased it....
    oh wait, my bad. i read that wrong.
    It's tube brushing season...93% done (39.35 miles of tubing)...only 1,242 tubes to go!

    Original member of the Raccoon Brotherhood.

    EVERYTHING IS AWESOME!!!

  9. #9
    Join Date
    Jan 2002
    Posts
    241
    So when you say you tested the switch you put the unit in test mode and kept the mag (and meter clamped across terminals on ohms) on it while you started just the exhaust fan and took readings every 2% or so (starting at min speed) as you were ramping the ex fan speed up at the HI, then started the evaporator fan and ran it at different speeds while you took readings every 2% or so and the same with the return fan. I have seen these switches flake out due to how they are mounted, they do not have an external low side tap on the xducer, its in the air stream. This can be affected by external sources ie your supply fan in the morning running wfo causing a neg pressure on that xducer low side input. Just for ****s and giggles take a piece of 1/4 fr tubing and run it down to the unit base pointed down so no water gets in it so it gets an OA reading on the low side and see if the issue stops.

  10. #10
    Join Date
    Apr 2011
    Location
    Chicagoland Area
    Posts
    37
    ZeroCool, what I mean by tested was I disabled the economizer until the unit got up and running (90% or better on the sf VFD) and then enabled the economizer again. It seems like the first time the unit begins to economize is when the problem occurs so I was trying to recreate that scenario. I definitely like you idea of running the low side to the OA. That should definitely work, wish I woulda thought of that. Lol!

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