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  1. #14
    Join Date
    Jul 2011
    Location
    Lehigh Valley, PA
    Posts
    427
    Quote Originally Posted by Brian8383 View Post
    So you are saying it runs with the t stat wires removed from the unit and jumpered R to Y to G? Or no?
    Yes. It will run jumped R--Y--G

    Try this. I had this happen to me once. A compressor on a unit was on its way out and over amping, but not enough to cause the breaker/fuse to trip. When it started it over amped it caused a voltage drop to the unit. 208 3 phase dropped into the high 100's(don't remember exactly how low it went) this caused the transformer voltage to drop also because it was being supplied less than 208 which caused the contactor to drop out because it was seeing in the high teens for a voltage.

    It happened so quick, my meter wasn't picking it up. As soon as the compressor started the voltage dropped and caused the contactor to drop out and chatter.

    To test this, put your meter on the transformer and push the contactor in and see if the 24v remains constant. Also, check the compressor amps and meg the windings if you have a megger.

    Unit had a failing compressor. Changed it out and of course the chattering went away. We also got an electrician fix a problem with the line voltage wiring to the unit adding to voltage sag.
    But it's been running since Friday jumped. If the compressor was going out....but I will be back on tues.

  2. #15
    Join Date
    Jul 2010
    Location
    napping on the couch
    Posts
    1,095
    Ok. I'm getting a bit of a handle on this. I would first look at the "Y" thermostat wire. You can disconnect all the wire from the stat and try to jump out R, G, Y up at the unit with the t stat wire hooked up ans see if it does chatter. If yes. Disconnect the t stat wire from the unit and ohm out each wire to the other wires. See if any are grounded. You may just have a pinched/melted/damaged t stat wire. If so, run a new wire. Or if you are a company like the ones we get accounts from, you can use another conductor in the s stat wire as long it isn't shorted. But, run a new wire. Doing it right will never bite you in the ass.
    In 1959, Cuba wanted "CHANGE" too.

  3. #16
    Join Date
    Jul 2011
    Location
    Lehigh Valley, PA
    Posts
    427
    Quote Originally Posted by Brian8383 View Post
    Ok. I'm getting a bit of a handle on this. If yes. Disconnect the t stat wire from the unit and ohm out each wire to the other wires. See if any are grounded. You may just have a pinched/melted/damaged t stat wire. If so, run a new wire. Doing it right will never bite you in the ass.
    You nailed it Brian. It was a melted section of stat wire which ran near the blower motor. Y was shorted to C. I could have eliminated the common wire but I didn't, I replaced the wire as you say. Thanks

  4. #17
    Join Date
    Jan 2010
    Posts
    5,817
    Good job Capz !
    Persistence pays off.

  5. #18
    Join Date
    Jul 2011
    Location
    Lehigh Valley, PA
    Posts
    427
    Quote Originally Posted by VTP99 View Post
    Good job Capz !
    Persistence pays off.
    Call me Cap. I wanted Cap when I registered but it was taken. so I added a Z. Now I should track down the real Cap. I wonder if a case of beer...
    Thanks

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