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  1. #1

    Hmm Goodman heat pump - blower motor run capacitor failed twice, what's wrong?

    Something has - I think - destroyed the motor run capacitor on my heat pump, but I am not sure what it is.

    Back story:

    I have a Goodman 3.5 ton heat pump, model ARUF036-00A-1A. Two nights ago I woke up to the smell of something electric burning, and the sound of the blower motor stalled while trying to start.

    The motor run capacitor is a 7.5uf and 370v, part number 27L566. I picked up a replacement capacitor, which is the same except it is rated 440v/370v at the recommendation of the local HVAC shop. This is a Mars #12931. I installed that, turned the HVAC power on, and it worked fine.

    At that time I noticed a transformer (see below, left side) in the air handler was buzzing, and I don't recall it making any noise before. I looked at it, and the fuse that is installed was not blown, so I buttoned things up.

    Last night I again woke up to the smell of something electric burning and a stalled blower motor. I turned the power off to the heat pump.

    I took photos of the heat pump innards, CLICK to get full-sized image:

    Transformer on the LEFT is buzzing:



    Motor run capacitor:



    Can someone tell me if this is a simple fix - is the transformer? Computer board? Or do I need to call someone?

    Thanks!

  2. #2
    Join Date
    Mar 2009
    Location
    Mount Holly, NC
    Posts
    3,118
    you need to call someone.
    ignore the buzzing, it's normal from the transformer.
    capacitors fail. and sometimes they are bad out of the box, but I'd have someone out to actually check out the system and find the fault.
    The TRUE highest cost system is the system not installed properly...
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    Dwane Johnson
    The A/C repairman

  3. #3
    Join Date
    Dec 2012
    Location
    Rancho Cucamonga, CA
    Posts
    22
    This is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

    You can find the rules for posting and qualifications here.

    Further infractions may result in loss of posting privileges.
    Last edited by beenthere; 12-14-2012 at 04:38 PM. Reason: Non Pro * Member

  4. #4
    Quote Originally Posted by Justhowe View Post
    I agree
    Thanks guys, I appreciate the advice.

  5. #5
    Thought you'd appreciate an update - the technician diagnosed the blower motor had failed. It has ... uh ... one of the windings grounded out. Basically, it is shorting out. In addition, it spins very poorly. I've ordered a new one and will have it installed.

    He also discovered that it was the wrong sized motor. The motor is one size too small, which he says can cause premature wear because it's working too hard, and additionally it causes poor airflow. Poor airflow has been a big issue since we moved in, so hopefully the correctly sized motor will fix that, as well as better heat/cool my house.

  6. #6
    Join Date
    May 2009
    Location
    Savannah, Ga/H.H. Island, S.C.
    Posts
    1,455
    Jesse J,

    Having a blower motor fail after run capacitor replacement is actually a regular occurrence. I always tell customers after I change a bad run cap on a blower that there is 50/50 chance of the blower dying within the next few weeks.

    My theory on this is below, I have no proof to back it up so take from it what you will.

    Blower run caps get weak over time. I believe that the prolonged restarting under a reduced valued capacitor causes the bearing/windings to fail prematurely.

    Condenser fan motors don't have the same issue because blower run caps are exposed to significantly less inrush current than a dual cap on a condensing unit. The dual cap fails when weakened enough that the inrush current blows the capacitor before the bearings/windings receive any damage.

    Hope that makes sense. And if this is completely inaccurate; someone feel free to correct me.

  7. #7
    That's interesting, thanks for the info.

    Now, onto new questions I forgot to ask.

    While the HVAC serviceman was here he noticed that one of the wires to one of the emergency heat strips was burned up, and you can actually sort of see it in the photo I took - it's burned all the way OFF of the connector and bubbled the wire coating:



    This clearly was the burning smell I noticed. So ...

    1. Does that mean my heat pump has been using the heat strips (emergency heat) during daily use?

    2. Shouldn't that wire be fused?

    I'm AMAZED and frightened that the wire burned up before something tripped, this just seems stupid dangerous to me! Yes, I know it's a big current draw, but I've used 30-50-100 amp fuses/breakers on car stereo applications, why wouldn't there be one here?

    I am also not thrilled that the emergency heat has been in use, because that just means a bigger bill for me. I'd rather use my portable oil-filled radiators if needed...

  8. #8
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,802
    The heat strips will come on during normal use if the heat pump can't maintain temp and during defrost. The electric heat wire probably burned due to them being on when the motor stopped blowing air over them so the overheated. It should have opened the high temp limit safety though.

  9. #9
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    4,989
    The model number you posted for your indoor unit does not match with the outdoor.

    You posted a 3 ton air handler, and you said you have a 3.5 ton outdoor.
    Not good, but unrelated.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  10. #10
    Join Date
    Jan 2008
    Location
    Texas
    Posts
    1,766
    Looks to me like loose connections at breaker. Breaker protects the loads downstream, the connections that got hot were upstream of the breaker.

  11. #11
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,910
    Quote Originally Posted by hvacvegas View Post
    The model number you posted for your indoor unit does not match with the outdoor.

    You posted a 3 ton air handler, and you said you have a 3.5 ton outdoor.
    Not good, but unrelated.
    I think he was calling his air handler a heat pump.
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  12. #12
    Join Date
    Nov 2009
    Location
    Kansas City
    Posts
    124
    They are not like batteries that get weak and you have to change them. A capacitor should stay the same forever. Remember the old capacitors that they used to put in units that had PCB in them, you can check the microfarads in them and they still have what they did 30 yrs ago. The parts made nowadays are just cheap crap from china. These capacitors I replace sometime only last 1 summer.mthey don't make things like they used to

  13. #13
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    4,989
    Quote Originally Posted by beenthere View Post
    I think he was calling his air handler a heat pump.
    Sheez. Using logic and junk.
    well....
    Then it's not a 3.5 ton, NOW IS IT! XD
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

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