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  1. #1
    Join Date
    May 2009
    Posts
    10

    Intermittent Blower Problem; Intertherm

    The feedback that I got from this site regarding static pressure and return duct sizing last year was a great help. When the owner of the company that installed the unit came out and I reviewed the feedback from this site and the static pressure readings that I had taken, he said that the feedback was exactly right and he had a crew back out here the next day to correct the undersized return duct. Thanks!

    We've got a 94 mobile home on our farm for our farm help.

    The blower motor stopped running yesterday. I removed the cover from the AHU compartment, and it appeared that the heating elements were heating up, but the blower would not start. There was just a slight hum from the blower motor. I turned the switch on the T-stat to fan, and no fan. Also turned the rocker switch at the unit from auto to fan and no fan. Turned the power off to the unit and built a fire in the wood stove.

    I started to try and check the unit out today, and the fan ran fine.

    Turned the heat on, heard the click of the relay and a few seconds later the fan came on in low. When the T-stat was satisfied, the heating elements clicked off and a little while later the blower turned off.

    I turned the T-stat to fan. The fan came on in high.

    I turned the rocker switch at the unit to on, and the fan came on in high.

    Nordyne/Intertherm Electric furnace:

    Model: FEBB-015HA
    Serial: FEB9403-05742
    "Multi-Speed Motor 3.0 FLA 1/3 HP"

    Motor:
    GE Motor
    MOD 5KCP39GGF564AS

    Black - Hi
    Blue - Med Hi
    Yellow - Med Lo
    Red - Lo

    Motor wiring:

    The red and green wires are not used and are wire capped off.

    Black wire to orange wire: 9.8 (on 200 ohm scale)
    Black wire to yellow wire: 7.7 (on 200 ohm scale)
    Orange wire to yellow wire: 8.2 (on 200 ohm scale)

    The orange wire is connected to a device that projects into the heating element chamber (limit switch I assume).

    The yellow and black wire are hooked to different terminals on a black plastic device mounted inside the wiring compartment (sequencer?).

    The T-stat terminals on the blower assembly are not used. The quick disconnects are not used either. Everything inside the electric compartment on the blower assembly have been abandoned in place. All wiring connections are with wire nuts.

    I'm going to clean up the blower and oil the motor.

    Any idea what is causing the intermittent problem with the blower?

    If it might be the T-stat, I still have the original Intertherm T-stat and could put that back on, but it has been on for a while and was working fine.

    I would like to add a T-stat that has a circulate function that would run the blower on low speed periodically to circulate the heat from the wood stove. Any suggestions on how to accomplish this?

    Thanks in advance for helping with this problem.

    Bill NC
    Last edited by Bill NC; 01-16-2010 at 08:11 PM. Reason: Clarification

  2. #2
    Join Date
    Mar 2001
    Posts
    1,213
    #1 - fan motor - probably overheated & shut off on internal thermal cut-out. Will happen again. When you call a tech in to replace the fan motor, let them know what else you want when you call>

  3. #3
    Join Date
    May 2009
    Posts
    10
    Thanks. I'll check the amps on the blower motor on high.

    Grainger has a 3 speed GE replacement motor for$, if memory serves me, it will be a little less if I put it on my account there.

    The capacitor & terminal guard would be under $, so I'd really want to make sure that the motor is bad and not just the capacitor.

    Bill NC
    Last edited by beenthere; 01-17-2010 at 02:15 PM. Reason: Removed prices

  4. #4
    Join Date
    Sep 2009
    Location
    Arnold mo
    Posts
    3,978
    Quote Originally Posted by Bill NC View Post
    Thanks. I'll check the amps on the blower motor on high.

    Grainger has a 3 speed GE replacement motor for , if memory serves me, it will be a little less if I put it on my account there.

    The capacitor & terminal guard would be under , so I'd really want to make sure that the motor is bad and not just the capacitor.

    Bill NC
    A motor that "hums" is not shut off due to internal overload. It it the sound of a motor that is trying to start but isn't getting the help it needs from its little helper. Well, it can be more complicated than that but that's why you need to get a professional to come out and do this stuff.
    Last edited by beenthere; 01-17-2010 at 02:15 PM. Reason: Removed prices from quote

  5. #5
    Join Date
    May 2009
    Posts
    10
    When I had a new Trane unit installed in my own house last year, and the HVAC contractor that installed the system put in a very restricted return air duct, I got a lot of good advice on this forum.

    http://hvac-talk.com/vbb/showthread.php?t=283622

    I bought a manometer and presented all the pertinent facts to the owner (whom I had worked with on a custom energy-star residential project that I built) he agreed and re-worked the return air duct.

    Just trying to learn something.

    Bill NC

  6. #6
    Join Date
    Feb 2009
    Location
    north of 49
    Posts
    233
    Quote Originally Posted by Bill NC View Post
    Thanks. I'll check the amps on the blower motor on high.

    Grainger has a 3 speed GE replacement motor for, if memory serves me, it will be a little less if I put it on my account there.

    The capacitor & terminal guard would be under, so I'd really want to make sure that the motor is bad and not just the capacitor.

    Bill NC
    A tech will be able to test the capacitor for you and tell you if it's bad or not. He will be able to test the motor for you also to tell you it it's bad or not. Sounds like you have a tester. I would tell you how but we can't give out DIY stuff and for good reason.
    good luck
    Last edited by beenthere; 01-17-2010 at 02:16 PM. Reason: Removed prices from quote

  7. #7
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,776
    Sorry, this is not a DIY site. So we are not allowed to give out DIY advise.

    Please read Site Rules Thank you.

    Call a contractor, he will be able to determine what is really wrong, and repair it.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  8. #8
    Join Date
    May 2009
    Posts
    10
    Quote Originally Posted by Moose View Post
    #1 - fan motor - probably overheated & shut off on internal thermal cut-out. Will happen again. When you call a tech in to replace the fan motor, let them know what else you want when you call>
    Apparently it was just a weak capacitor. The 7.5 MFD capacitor tested at 2.7. Replacing the capacitor brought the motor amps back down into specs and solved the problem. It would seem that the weak capacitor was increasing the motor amps, heating up, and kicking out the thermal cut-out.

  9. #9
    Join Date
    Mar 2001
    Posts
    1,213

  10. #10
    Join Date
    Jan 2010
    Posts
    97
    Good job Bill, the more you know the better off you are.

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