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  1. #1

    2 stage furnace and central a/c HELP

    Ok - here we go. two years ago we had a 95% efficient 2 stage Frigidaire furnace installed. The following year we had a 16 seer high efficiency 2 stage central ac installed along with the air handler.

    Today the central ac stopped and I checked the fuse box and nothing was triggered.

    I called the guy who installed it and his phone is disconnected.

    I had someone else who was referred to me come out today. He went right to the outside ac unit. He pulled off the side cover where the wiring is. He looked puzzled. He told me that the unit was not wired properly. He said the brown wire that runs from inside the house to the unit only has two wires inside. He showed me and it was a red and white wire under the brown wire sheath.

    He told me that for a 2 stage system, it is 100% impossible to only have 2 wires connected to the outside unit, he says more were needed and should have been run in the first place. He said multiple wires were needed to make the 2 stage system work.

    He then went into the basement and opened up the furnace (gas). He then said something else was wrong. He said all of the switches on the boards were not configured at all and must have been left in the position that the factory shipped it in. He said that they need to be adjusted (some up and some down) based upon the factory guidelines, and that my whole system has been running on 1 stage the whole time.

    Is all of what I am being told correct?

  2. #2
    Join Date
    Jan 2009
    Keokuk, IA
    Very possible. The first contractor being out of business is a clear red flag. Sounds like he was a hack, pooerly trained or worse, his company forced him to cut corners.

    I'd get thsi contractor ot pull a new wire to the thermostat so you have 2 stages cooling and 2 heating, then a new wire to the condenser so you have 2 stage cooling.

    Then, if it were me. I might have him check pressures on the AC unit, and if it's not right on hte money... I'd assume it wasn;t installed corerctly, and pull the refrigerant, replace the fitler dryer, pump down the system and weight back in hte correct charge for that unit.

    A installer that overlooks the correct number of control wires, likely didn't follow other proper practices and is not out of business for a reason.

  3. #3
    thank you for your reply. He pulled new wires while he was there and also adjusted the switches on the circuit boards on the furnace. He also reprogrammed the honeywell thermostat so that it recognizes the 2 stage system.

    is it true that it couldn't run on 2 stages with only a red and white wire going into the central ac outside?

  4. #4
    Join Date
    May 2000
    Indianapolis, IN, USA
    No, you cannot run in 2 stages with 2 wires. You would need 4 to power the Comfort Alert module and have 2 stages of cool. Sounds like your 2nd guy was as competent as the 1st guy was incompetent.

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