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  1. #1

    Confused Help figuring out my HVAC system...

    I have a Trane XR-13 Heat Pump(HP) outside with a
    Carrier FC4BNF036 Air Handler(AH) inside. I am
    tryting to figure the system out because I tried
    putting in a new programmable thermostat.

    Thermostat wires:
    R, Blk, O, Y, Grn, W
    Air Handler wires:
    R---> Fan
    Blk---> Fan and pass-thru to HP
    O---> Pass-thru to HP
    Y---> Pass-thru to HP
    Grn---> Fan
    W---> Heat strip? and pass-thru to HP
    Heat Pump wires:
    Blk---> a couple connections, common
    O---> 9-pin (3x3) connector on board
    Y---> 'Coil' connector on board
    W---> 'Ambient' connector on board

    I ohmed out the thermostat:
    Heat: RH shorts to Y1 and W2
    Cold: RC shorts to Y1, Y2, and O
    Em. Heat: RH shorts to W1 and E

    My thought was to wire the HP Coil wire to Y1
    on the TS so it should be activated whenever
    heat or cold are called for. Then wire O on the TS
    to O on the HP for the reversing valve. The white
    wire was going to what looks like a couple
    heating coils in the air handler. I assumed this
    was emergency heating since the HP should take care
    of both heating and cooling, but it looks like the
    signal is also passed through to the HP. The AH fan
    and HP fan both run as expected they should. Cold air
    (not ambient, but colder) comes out in cool mode,
    but only ambient air comes out when heat is called for.

    I know the White wire passed through to the HP is an
    issue. The wiring diagram on the HP shows it going to
    an 'Optional' circuit with a thermister. Perhaps when
    Emergency heat is called for, the white wire activates
    both the heating coil in the air handler, and turns on
    the outside fan for air volume?

    I would really appreciate some help with this as I've
    spent HOURS tracking down the wiring.


  2. #2
    Join Date
    Apr 2008
    Alberta Canada

    What is so hard About that.

    Are you in the trade or a home owner.
    Do it right the first time.

  3. #3
    Join Date
    Jun 2007
    Round Rock
    You are not going to get any help in here from anybody. You will most likely take a beating and the thread will get closed.

  4. #4
    Home owner, but an electrical engineer.

    What would I take a beating for? I asked the question in an intelligent
    and concise way.

  5. #5
    Join Date
    Jan 2004
    For not reading the rules of teh site.
    Or this from the top of this page.

    Questions and discussions pertaining to HVAC for the home. No pricing, no DIY, please read Site Rules
    Contractor locator map


    How many times must one fix something before it is fixed?

  6. #6
    Join Date
    Jan 2004
    Hate to tell you. But your not getting 13 SEER with that mismatch system either.
    Contractor locator map


    How many times must one fix something before it is fixed?

  7. #7
    Join Date
    Jul 2004
    Clearly things are being done to save money here. Wrong approach. You have a mis-matched system for starters, the people/person who installed the Trane outdoor unit did not do a Manual 'J' load calc and then replaced a non-matching outdoor unit with an existing indoor unit. From where I sit, that type of situation doesn't even warrant a second look. You need to find a company capable of that work and get your answers from them.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  8. #8
    Join Date
    Dec 2006
    Middle Tennessee


    give the guy a break, he is an engineer


  9. #9
    Join Date
    Jun 2004
    Howell, Michigan
    Please read the site rules, there is a link in my signature line.

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