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  1. #1
    Join Date
    Aug 2006
    Location
    Windsor area Ontario Canada
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    Carrier Edge dropping out when limit opens new install

    Just had installers install new 96% 2 stage carrier downflow with new AC and edge thermostat. Customer called few days later because of no heat, found it going off on limit, gas pressure wasn't adjusted properly by installers but is now good (1.3"wc 1st stage , 3.5"wc 2nd stage) but was still going off on limit, found duct issues in crawl space we are fixing on Monday but customer noticed whenever furnace went off on limit the thermostat went blank, carrier edge stat, the one with 2 wires from stat to control module (Vg & V+) and 5 wires from control wire to furnace (r,w,y,g,c)
    Just wondering if anyone has ever seen this before?
    This furnace is doing strange things and I plan to go there monday, they also said there was a bunch of smoke coming from furnace because blower didn't start, my tech went there and no smoke and blower started everytime.
    Any ideas on either of these? I have never heard of a limit dropping power to thermostat, i will update info on monday when i look for myself.

  2. #2
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
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    A lot of furnaces do that.
    It’s a way to let the customer know there is something wrong, because otherwise it would go unnoticed.

  3. #3
    Join Date
    Aug 2006
    Location
    Windsor area Ontario Canada
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    Thread Starter
    I've honestly never seen it before and i have been in the trade for 15 years, is it just communicating stats that do this?

  4. #4
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
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    Quote Originally Posted by markmast View Post
    I've honestly never seen it before and i have been in the trade for 15 years, is it just communicating stats that do this?
    nope.

    One I can think of specifically would be Tempstar/ICP products. Cant remember the model, but the ones that have the stainless steel front covers.

    Some older Janitrols would do the same thing.

    It just kills R out of the board.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  5. #5
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
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    Carrier does that. Drops R when the limit opens. Why is the limit opening? Oversized furnace comes to mind.

  6. #6
    Join Date
    Jul 2007
    Location
    Virginia
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    Quote Originally Posted by markmast View Post
    I've honestly never seen it before and i have been in the trade for 15 years, is it just communicating stats that do this?
    No.

    As you can see from the attached wiring diagram, 24 volts from the transformer passes through the limit and Rollout switches before going to the “R” terminal on the furnace control board.

    If that “R” terminal loses 24 volts because any of those limits are “OPEN”, the control module will lose power, and subsequently the thermostat will lose power.
    Attached Images Attached Images
    Instead of learning the tricks of the trade, learn the trade.

  7. #7
    Join Date
    Aug 2006
    Location
    Windsor area Ontario Canada
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    Thread Starter
    Thank you for the input, appreciate it,
    It is going off on limit because the duct work is restricted, i am not sure how the old one worked but the return is just a box in the crawl with 2 - 6" flexs over to 2 returns in the house, definitely not enough, and one of those returns were covered by furniture when my tech went there. Also the supplies all had media filter stuffed in them, restricting air flow and the supply has a piece of 12" flex in between 2 pieces of rectangle duct so there is a few things we need to address here.

  8. #8
    Join Date
    Dec 2007
    Posts
    9,114
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    Maybe the smoke was the oil burning off.
    The Food Stamp Program, administered by the U.S. Department of Agriculture, is proud to be distributing the greatest amount of free meals and stamps EVER.
    Meanwhile, the National Park Service, administered by the U.S. Department of the Interior, asks us to "Please Do Not Feed the Animals". Their stated reason for this policy "... the animals become dependent on handouts and will not learn to take care of themselves."
    from an excerpt by Paul Jacob in Sun City, AZ

  9. #9
    Join Date
    Mar 2017
    Location
    ORE.
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    22
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    Poor air flow
    Gotta be a ductwork issue. Test static?
    Replace like for like BTU wise?



    Sent from my iPad using Tapatalk

  10. #10
    Join Date
    Aug 2009
    Location
    Rhode Island
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    A lot of furnaces drop R especially older ones, see it a lot when customers want wifi tstats and they wont always work

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