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  1. #1
    Join Date
    Aug 2003
    Posts
    27

    Confused

    My neighbor's A/C unit runs when their furnace turns on. I told them last winter that is was running when it was cold at night. They said they would call someone to fix it. All they did was shut the circuit breaker off, because you could hear it click all winter long.

    Now it is running again. When the steam comes out of the chimney the A/C unit runs and stops when the steam stops.

    It going to be 2 degrees tonight. Will it stop or break? And think about this a $500 gas bill and a $500 electric bill!

  2. #2
    Join Date
    Dec 2006
    Location
    Lansing, Iowa
    Posts
    8

    A/C running when the Furnace is?

    That sounds like a short in the thermostat control wiring or someone has the wires hooked up on the same sending line for the heat control side. You have 2, 24 volt wires running from Condenser A/C unit to the Furnace unit usually. One is a temp control and the other is a ground. If you have the control wire from the condenser hooked up to the sending for heat line. They both could run. *Usually.
    because of a demand call from the thermostat. This COULD be the problem. I'm not saying I'm for sure.

  3. #3
    Join Date
    Dec 2006
    Location
    Lansing, Iowa
    Posts
    8

    hey wait a minute

    if they have the breaker off to the condenser A/C unit and there's no electricity to it. Then it shouldn't run at all.
    Either they donot have the correct breaker Off, or there's a wiring problem there.

  4. #4
    Join Date
    Mar 2005
    Location
    Indianapolis, IN
    Posts
    241
    Are you sure they have A/C and not heatpump with gas backup?


  5. #5
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,897
    They'll destroy the compressor before the winter is over. Not to mention have a big gas & electric bill!

  6. #6
    Join Date
    Nov 2006
    Location
    Gloucester Virginia
    Posts
    20

    Wink

    even if it is a dual fuel system the heatpump and furnace shouldnt be on at the same time with the exception of defrost;}
    heattech

    If it hasnt worked properly since you serviced it last then why did it take the customer 2 years to complain??

  7. #7
    Join Date
    Jul 2006
    Location
    NW burbs of Detroit
    Posts
    6,058

    Re: A/C running when the Furnace is?

    Originally posted by woodheat
    [B . One is a temp control and the other is a GROUND.
    [/B]
    I did not know a 24 v xfrmr had a "ground".

    Common, yes, a 24v side, yes.

    Is the terminology somewhat lacking?

  8. #8
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,704

    Re: Re: A/C running when the Furnace is?

    Originally posted by hvaclover
    Originally posted by woodheat
    [B . One is a temp control and the other is a GROUND.
    I did not know a 24 v xfrmr had a "ground".

    Common, yes, a 24v side, yes.

    Is the terminology somewhat lacking? [/B]

    all lennox furnaces "ground" the common side of the transformer, sure there has to be others that do to.

  9. #9
    Join Date
    Mar 2005
    Location
    Indianapolis, IN
    Posts
    241
    Originally posted by heattech
    even if it is a dual fuel system the heatpump and furnace shouldnt be on at the same time with the exception of defrost;}
    OP is clueless of that fact, for all we know it could be water-heater, or fireplace. Just because "steam comes out of the chimney" not always equal furnace is running.

  10. #10
    Join Date
    Aug 2003
    Posts
    27
    It's still trying to start. You can hear the compressor trying to start for about 10 seconds, then the sound stops and just the fan is running.

    My electrical service goes to same post as my neighbors and my lights dim a little like a motor is trying to start.

    And besides I though a heat pump is only good to about 40 degrees, not 2 degrees. It has been below freezing the last 5 days.

  11. #11
    Join Date
    May 2006
    Location
    east central indiana
    Posts
    1,117
    Some run a heat pump all the way down to 0 degrees.
    At any rate, it sounds as though that compressor may have finally slugged itself to death

  12. #12
    Join Date
    Aug 2003
    Posts
    27
    I just hear a click. No more fan sound or compressor trying to start for 10 seconds. Maybe they shut the circuit breaker off or it's tripped.

    I'll tell you if/when there's a new unit on the outside.

  13. #13
    Join Date
    Sep 2003
    Posts
    1,311
    It could also be that they have a heat pump thermostat or a thermostat set for heat pump.

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