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  1. #1

    Hard start capacitor exploding

    I would love some advice because the information coming from my HVAC tech just doesn't make sense. I am sorry that I am likely getting terms wrong here.

    We've lived in my house for a little under a year. When we moved in, during the summer, the fan on our outside unit wasn't able to start up so I had a tech come out and fix it. He said that the start capacitor was blown and installed a new one along with a start boost which was not on the before. Two days later the fan was not turning on again and the tech came back out and the hard start had exploded. When I say exploded I really mean it. All the guts were everywhere inside the unit.

    Now a few weeks ago I had the system serviced for winter, and the hard start was blown again. The system had worked wonderfully, and I had even checked every now and then that the fan really was starting up. Everything seemed normal. It was even working when the tech opened the unit and discovered this.

    The tech is recommending we get a static pressure test done to find out why this hard start is blowing. To me this doesn't make sense. The static pressure test checks how the air is moving through the duct work inisde the house. My issue is with the unit outside, not the inside unit. We don't have any cold/warm spots and I can't understand how the two could be related.

    What would cause one of these capacitors to explode?

  2. #2
    Join Date
    Jul 2007
    Location
    Mount Airy, MD
    Posts
    7,281
    Start capacitors can explode from an improperly sized/malfunctioning potential relay (this controls the start cap) but doubt that's the issue. It is more then likely improperly wired and powered during the "off" cycle

    Sounds like you need to get a second opinion from another contractor.

  3. #3
    Join Date
    Aug 2002
    Location
    Southold.calm
    Posts
    5,859

  4. #4
    Thank you for your response. I will get someone else to come out and look at it.

  5. #5
    Join Date
    Dec 2004
    Location
    newton,mass.
    Posts
    6,109
    Quote Originally Posted by epsolon77 View Post
    I would love some advice because the information coming from my HVAC tech just doesn't make sense. I am sorry that I am likely getting terms wrong here.

    We've lived in my house for a little under a year. When we moved in, during the summer, the fan on our outside unit wasn't able to start up so I had a tech come out and fix it. He said that the start capacitor was blown and installed a new one along with a start boost which was not on the before. Two days later the fan was not turning on again and the tech came back out and the hard start had exploded. When I say exploded I really mean it. All the guts were everywhere inside the unit.

    Now a few weeks ago I had the system serviced for winter, and the hard start was blown again. The system had worked wonderfully, and I had even

    checked every now and then that the fan really was starting up. Everything seemed normal. It was even working when the tech opened the unit and discovered this.

    The tech is recommending we get a static pressure test done to find out why this hard start is blowing. To me this doesn't make sense. The static pressure test checks how the air is moving through the duct work inisde the house. My issue is with the unit outside, not the inside unit. We don't have any cold/warm spots and I can't understand how the two could be related.

    What would cause one of these capacitors to explode?

    Are you sure that he said the start capacitor was bad? I think maybe he meant run capacitor, it would be bad to put a hard start capacitor (relay) on a start capacitor. Is the hard start the right one ... voltage and capacity?

    .
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  6. #6
    Join Date
    Dec 2001
    Location
    Ocean Pines, MD
    Posts
    6,997
    Is this by any chance a Trane or American Standard system?

  7. #7
    This is a Bryant unit about 4 years old. The first tech's notes were "Found the o/s unit not running due to a bad dual capacitor, replaced capacitor and installed hard start kit."
    I have no idea if it is the correct voltage or size. The company is a very reputable bryant authorized dealer though. I know that doesn't mean they get it right 100% of the time, but at least they are used to servicing Bryants.

  8. #8
    Join Date
    Sep 2005
    Location
    Atlanta GA area
    Posts
    21,407
    Quote Originally Posted by epsolon77 View Post
    This is a Bryant unit about 4 years old. The first tech's notes were "Found the o/s unit not running due to a bad dual capacitor, replaced capacitor and installed hard start kit."
    I have no idea if it is the correct voltage or size. The company is a very reputable bryant authorized dealer though. I know that doesn't mean they get it right 100% of the time, but at least they are used to servicing Bryants.
    Dual capacitor is the run capacitor. Hard start capacitor is different.

    Run caps (capacitor) tend to be sensitive to things like voltage surges, lighting strikes close by, overloads, voltage drops, and many other things, some of which are not electrical... Having said this there are a lot of details we do not know from the internet.

    The current tech could be right, or he could be missing something. I would get a second opinion.
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  9. #9
    Join Date
    Nov 2008
    Posts
    1,673
    Quote Originally Posted by epsolon77 View Post
    Two days later the fan was not turning on again and the tech came back out and the hard start had exploded. When I say exploded I really mean it. All the guts were everywhere inside the unit.
    Whatever cap you put in, monitor the case temperature-rise-above-ambient-temperature. for a few hours and compare with manuf. spec's.
    Failing in only two days is some pretty serious abuse.

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