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  1. #1
    Join Date
    Aug 2008
    Location
    Scottsdale,AZ
    Posts
    52

    capacitor sparking

    I was called on a svc call yesterday to a trailer. Nordyne air handler with heat strips.
    Anyway my cust said he coulkd smell a burning smell from the blower section.
    I Started the unit up and saw spark flying out the back of the motor.
    Replaced blower motor and run cap.
    later realized the spark was coming out of the capacitor.
    I got called back today because he said it was doing the same thing. I found the run cap to be black around the terminals, and the electrical tape i had around the terminal were melted.
    what is going on?
    noticed the blower relay. when I had the unit in cooling, the relay was 0V acroos cooling terminals and 50V (weird!!!) across heating terminals.
    switched to heating, had OV across heating terminals and 45V(weird) accross cooling terminals.
    why would the capacitor spark?
    thanks for any help

  2. #2
    Join Date
    Jul 2008
    Posts
    53
    Loose connections would be my first thought. Either the spade connection, or where the spade connection is crimped on the wire.

  3. #3
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,117
    Because you didn't fix the problem. You only addressed the symptom.

    When he calls you later today or tomorrow. Actually check out the unit.

    Since this is not a DIY site. You won't get any more help then that in the open resi forums.

    If you are in the trades, get your post count up to 15, and apply for pro membership. Then you can post questions like this and get technical answers.
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    How many times must one fix something before it is fixed?

  4. #4
    Join Date
    May 2000
    Location
    Urbandale IA. USA
    Posts
    4,934
    The motor acts like an auto-transformer.
    There will always be a voltage difference between HIGH (cool) and MED (heat), when one of them is energized.
    As to why the capacitor is burning up, check the voltage rating on it's lable then measure the voltage WHILE the motor is running.
    If you are a DIY and don't know how to use a multi-meter, disregard everything I just told you, and CALL A PRO.....
    Those who dance, appear insane to those who do not hear the music.
    Those who believe, appear ignorant to those who do not know God.

  5. #5
    Join Date
    Aug 2008
    Location
    Scottsdale,AZ
    Posts
    52
    the motor that was there asked for a 7.5 uf run cap/370V.
    the new motor is asking for 5uf /370V.all my connections are good and tight and checked the wiring diagram to make sure it was all properly wired.
    so if my voltage at the capacitor is over 370v will i solve the issue by putting a 440V run cap?
    what if the voltage is below 370 and it still sparks?

  6. #6
    Join Date
    Aug 2008
    Location
    Scottsdale,AZ
    Posts
    52
    Quote Originally Posted by beenthere View Post
    Because you didn't fix the problem. You only addressed the symptom.

    When he calls you later today or tomorrow. Actually check out the unit.
    thank you for your fantastic comment. I did check out the unit... there is only so much to check out. 1blower motor 1 blower relay 2 heat sequencer 2 heat strips and 2 breaker.
    everything is tight. and works fine for the 1st 6 hours or so...

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,117
    Quote Originally Posted by fadelG View Post
    thank you for your fantastic comment.
    Your welcome.

    You missed something or you wouldn't have been called back.
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  8. #8
    Join Date
    Aug 2008
    Location
    Scottsdale,AZ
    Posts
    52
    I know I am missing something somwhere. I poured water down the drain pan to make sure it wasn't leaking any water down through the blower section. the sequencers and heat strips wouldn't have anything to do with all this. temp split, superheat and subcooling all are perfect. and for the unit to be working fine for 5-6 hrs and all of a sudden start sparking at the capacitor just doesn't make sense to me.
    I am just looking to see if anyone had seen this before and see if anyone had some suggestions for this.

  9. #9
    Join Date
    Feb 2008
    Location
    Dallas & Longview, TX
    Posts
    629
    Quote Originally Posted by fadelG View Post
    the motor that was there asked for a 7.5 uf run cap/370V.
    the new motor is asking for 5uf /370V.all my connections are good and tight and checked the wiring diagram to make sure it was all properly wired.
    so if my voltage at the capacitor is over 370v will i solve the issue by putting a 440V run cap?
    what if the voltage is below 370 and it still sparks?
    If the new motor is labled for 5/370 then that what you use. If it's voltage is higher or the cap is still sparking then the pro side of this forum is where I'd start lookin.

  10. #10
    Join Date
    Aug 2008
    Location
    Scottsdale,AZ
    Posts
    52
    thanks I am new to this forum since this morning and am trying to get my posts to 15 to get to the pro section. thanks again

  11. #11
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,117
    Your making false assumtions.
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  12. #12
    Join Date
    Mar 2005
    Location
    Suppy NC
    Posts
    4,513
    is the cap attached to the blower housing or just hanging or taped up

    if it isnot grounded and the motor grounded properly you will continue to have problems.

    did you put in the correct hp and rpm motor if not you can also cause the volts in the cap to climb

    recheck all your connections

  13. #13
    Join Date
    Aug 2008
    Location
    Scottsdale,AZ
    Posts
    52
    the cap is resting at the bottom of the unit and the connections are taped all around with electrical tape to prevent from touching/shorting on anything.
    the motor is same hp same voltage.

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