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    ROLLINWJESUS Posts: 6, Reputation: 2
    New Member

    Mar 6, 2006, 08:23 PM
    Inducer motor overheats (carrier brand furnance)
    I replaced my inducer motor on my furnace due to the old one was bounding up. Now the new one runs find in low speed but once the furnace kicks into the second stage the inducer motor shuts down(in high speed) which I believe the thermal overload(built in) opens causing my furnace shut down. When the motor shuts down. What would cause this motor to shut off on overload protection and it seems to running fine. I was thinkinking the built in O.L. was undersized until I exchange that motor for another one and I still have the same problem.
    labman's Avatar
    labman Posts: 10,580, Reputation: 551
    Uber Member

    Mar 6, 2006, 09:04 PM
    How many wires des the motor have, just 3, or a whole handful? If the latter, you may not have the right ones selected. I can't tell you which ones you need. You may need to go over the installation guide for it carefully and perhaps call tech service if you have a number for whoever made the motor.
    ROLLINWJESUS Posts: 6, Reputation: 2
    New Member

    Mar 6, 2006, 09:40 PM
    The Motor Has 3 Wires A Neutral,low Speed Hot,high Speed Hot
    letmetellu's Avatar
    letmetellu Posts: 3,151, Reputation: 317
    Ultra Member

    Mar 6, 2006, 09:56 PM
    If you have an amp meter or a volt meter you need to check the voltage going to the high speed when the furnace kicks into high heat. It sounds like to me, from the way you described it, the inducer motor stops as soon and the switch is made, if that is the case maybe for some reason the voltage is getting to the motor. Is it possible that you may have used the wires on the wrond terminals. The furnace and its components are polarity sensitive. So even if you used the coded wire as the neutral itcould be wired wrong in the plug-in box.

    Also if the motor runs on high for a short period and then cuts out on internal protection that also sounds like you have the fields connected to the wrong wires. Best way to check is with a voltage meter.
    labman's Avatar
    labman Posts: 10,580, Reputation: 551
    Uber Member

    Mar 7, 2006, 05:45 AM
    Only having 3 wires makes it much easier to wire properly. Have you removed the motor and bench tested it to make the problem is the motor itself? Applying power to each winding separately and making sure it stops when it still has power to the high speed winding?
    ROLLINWJESUS Posts: 6, Reputation: 2
    New Member

    Mar 7, 2006, 06:35 PM
    Yes I have took the motor out and bench tested it, but it does not trip on overload. Where I bench tested doesn't have the same surroundinding temperatures as the furnace. I am wondering if my furnace is running to hot. The vent piping is not the problem I already check. Is there any other reason you can think of that would cause motor to overheat. It turns freely it will run all night long running in low there some type of air ciculation problem?
    labman's Avatar
    labman Posts: 10,580, Reputation: 551
    Uber Member

    Mar 7, 2006, 07:28 PM
    Are you sure it is the overloads killing it and not the furnace controls shutting off the power? Does the motor feel hot when it quits?
    ROLLINWJESUS Posts: 6, Reputation: 2
    New Member

    Mar 8, 2006, 05:28 AM
    The motor is hot I have sat there and seen the motor turn off and checked it with my wiggie and power is still there and also check for continunity through the motor and it reads open
    tkrussell's Avatar
    tkrussell Posts: 9,655, Reputation: 724
    Uber Member

    Mar 8, 2006, 02:29 PM
    Well Labman and let have offered good troubleshooting tips to test the motor, and you have come back with reasonable answers.

    Seems that the motor is getting too hot that the internal OL is tripping. To double check this, check for power at the motor leads once the motor has shut down, this will confirm there is nothing in the furnace controls shutting off the motor, as labman noted.

    Does the IM bolt directly to the furnace heat box? I remember there is usually a heat resistant gasket between the motor/fan frame and the heat box of the furnace. If this is not there or damaged heat from the box will transmit to the motor and cause the OL to trip from this contributory heat.

    I don't remember that the area the IM sits being abnromally hot. Again this would cause the motor temp to rise and trip. However, the IM is certainly surrounded by heat, but it would need to be very hot ,and I think may take some time, if the heat is ambient air and the air needs to heat the motor too high.

    The bolted connection would transmit heat much more quickly, and is where I think the heat is coming from. All your tests, esp. the benchtest seems to direct the cause to this somehow.

    Another think I just thought of is that there may be too much heat being drawn from the heat box through the fan's normal air draw, now this is a long shot, because the heat exchanger is dirty or otherwise clogged. I think that if the environmental air being passed over the heat exchanger cannot extract enough heat that this may cause excessive heat to exist and remain in the heat box, causing more heat to be available in the cumbustion chamber thereby affecting the inducer motor.

    Do either of thses suggestions make sense? I hope so, this is the best I can come up with for reasonable causes. Get back with more questions if not and we can continue with ideas, and If so, let us know what you found to correct it.
    ROLLINWJESUS Posts: 6, Reputation: 2
    New Member

    Mar 8, 2006, 06:15 PM
    Boy I feel bad I had you guys picking your brains out. There was a plastic wheel on this motor. Guess what that was for. It's a cooling fan. I was just about to put a fan on a bench to cool this motor off. I had to order the cooling wheel I am pretty sure that is the problem thanks guys
    reefact's Avatar
    reefact Posts: 1, Reputation: 1
    New Member

    Aug 13, 2009, 09:00 PM
    TkRussell ROCKS!
    I have had a problem where the inducer motor burned out and I replaced it. After replacement the heater would run for about 15min and then shutdown. I checked everything and finally googled my problem and found this thread. To test tkRussell theory I placed a small fan near the inducer motor and start the heater. It ran for 35min before I turned it off. Note that it never got past 20min out the outside. I will be getting a replacement gasket that was damaged when the motor was removed and a new fan for the motor. I'll let you know how this goes.

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