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  1. #1
    Join Date
    Mar 2009
    Location
    Southern Alberta
    Posts
    34

    Lennox XC13 Condenser

    I spent some time this past week changing a compressor that had been deemed "failed" by one of our other service techs about a week ago. He had also ordered a condenser fan motor and stated on the work order that the comp was tripped out on high pressure due to the condenser fan failure. This made me wonder and decided to re-diagnose prior to going through the hassle of changing the comp.
    I pressed in the contactor and the condenser fan turned on, but no compressor. Threw the amp clamp on, pulling 78 amps and then tripping on internal overload. I checked the capacitor and it was good, checked the windings of the compressor to each other and to ground and the readings were a little wonky, so I decided to change the compressor out.
    I then went to do a start up and had the same problem, no compressor! It was pulling 78 amps and tripping out. I looked at the wiring diagram and noticed that the black and red wires on the load side of the contactor were reversed from the diagram. I flipped them not expecting any change because it is single phase 240 V at the unit, but low and behold it fired up and ran like it should. Black went to common on the comp and red went to Run (after changing the wires).
    Why would it make any difference what wire went to the common or run terminal on the compressor? Isn't it the same voltage being applied to each leg?

  2. #2
    Join Date
    Mar 2009
    Location
    Southern Alberta
    Posts
    34
    I also had this problem with a condenser fan rotating the wrong way. I changed the wire going to T2 with the one going to the capacitor and the direction changed. What is confusing me is that I thought that you could only change direction with 3 phase by switching wires?

  3. #3
    Join Date
    Sep 2006
    Location
    Northern Colorado
    Posts
    12
    The capacitor common must be hooked up to the pole opposite the compressor common. By reversing only the wires to the compressor it removed the start winding from the circuit.

    Benjamin

  4. #4
    Join Date
    May 2009
    Posts
    6
    1. The run and start terminals are connected to the same phase with the cap in series with the start.

    2. Connecting the cap to the run winding instead of the start winding will cause a fan motor to turn backwards and overheat.

  5. #5
    Join Date
    Jun 2007
    Location
    Round Rock
    Posts
    3,587
    You probably could have switched the common on the capacitor and accomplished the same thing. I had this unit a few years ago we changed out. The unit would not run. I switched the line voltage wires on the bottom of the contactor and it started working fine. Just like you would on a 3phase when it doesn't work.
    I like DIY'ers. They pay better to fix.

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