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Thread: Blowing fuses

  1. #14
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    Oct 2004
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    Quote Originally Posted by mmj614 View Post
    you'll be surprised what you find in between. I've had a few that look clean from either side but caked on the inside. You're pressures and amperage are pointing to that as well. Sprinkler on the condenser is only masking the problem and just confirms that'...if it was electrical or otherwise the sprinkler wouldn't make a difference.
    How do you figure? Yes the coils are more than likely dirty and need to be split and cleaned but he is currently running over nameplate FLA at 270 head. IMHO you will still have some work to do after you clean those coils.

  2. #15
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    Jun 2008
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    Quote Originally Posted by jemawalton View Post
    How do you figure? Yes the coils are more than likely dirty and need to be split and cleaned but he is currently running over nameplate FLA at 270 head. IMHO you will still have some work to do after you clean those coils.
    Are you saying that even though the coils are dirty that this would not be a cause for higher than normal discharge pressure and higher amperage?

  3. #16
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    Quote Originally Posted by mmj614 View Post
    Are you saying that even though the coils are dirty that this would not be a cause for higher than normal discharge pressure and higher amperage?
    Higher than normal yes but not above FLA and certainly not above FLA at 270psi.

  4. #17
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    Sep 2003
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    Well the owner called me today, because of course he's still repacing that fuse. I told him that I'm recommending spliting the coils for cleanung as a starting point. I told him to call the office to scedule. We are so busy, I don't now when we will be back.

  5. #18
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    Mar 2006
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    cincinnati, ohio
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    Thumbs up

    Have you checked the cap and also do you have a voltage drop across your contactor?
    Knowledge comes with experience

  6. #19
    Join Date
    Mar 2008
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    71
    Quote Originally Posted by nickellhead View Post
    Have you checked the cap and also do you have a voltage drop across your contactor?
    This is a commercial unit,probally three phase. Clean the coils first, can't properly diagnose until you do. after you split the coils you will know for a fact tht whoever told you it doesn't matter doesn't know. Also, after you replace the fuse let it run about 30-45 min then kill power and check the temp. of the fuse. if it is hot to the touch the problem is a bad disconnect creating heat at the fuse wich causes it to blow. change the disconnect.

  7. #20
    Join Date
    Dec 2007
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    Southern, CA
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    I'm with the first and one above in thinking disconnect. Had a unit I'd find with blown fuses every PM, it always checked OK. Finally one time I went up and found all the disconnect's guts blown all over the roof. If its GE lever type with a vertical rectangle stamped into the front cover I can almost guarantee its bad. I would also look at voltage supply, both compressors are running higher amps than they should, and dirty coils will do that, but as a result of higher pressure. You don't have pressures high enough to account for it. So before tearing into the coil check the voltage at several points, it only takes a minute or two. If we're wrong we'll shut up about it.

  8. #21
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    Jul 2008
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    nw ohio
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    I agree with cleaning the condensers. But in my experience a bad discounct that has copper ended fuses in it tend to discolor one end or the other. Its easy to diagnoise these.

  9. #22
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    Sep 2003
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    Western PA
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    Our company has not weny back to this call as of yet. It was brought up in our service meeting. The service manager is leaning toward the disconnect. He also said he does not like using fused disconnects on 3 phase equipment.
    When I was there, I checked the voltages and had less than half a percent of imbalance. And there were no loose connections or heat coming from the disconnect.

  10. #23
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    Dec 2007
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    Southern, CA
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    balanced is good, what was the voltage?

  11. #24
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    Sep 2003
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    Quote Originally Posted by Coolmaniac View Post
    balanced is good, what was the voltage?
    208,207,209

  12. #25
    before changing disconnect look at compressor #2 running over rated amps. dirty condenser might not be the problem with compressor #1 running good head pressure. i would look for an overcharged circuit with compressor #2 because higher pressures equals higher amps. also low superheat on circuit #2 which means you are close to flooding back, another sign of an overcharge.

  13. #26
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    Sep 2003
    Location
    Western PA
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    Update. The first Tech that diagnosed the blower motor as the problem was sent back. He now says it's the disconnect. I'll let you all now if changing the dissconnect does not fix the issue.

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