Adding Econo-mode to a Window Unit A/C

Discussion in 'General Electronics Chat' started by Steve0701, Jul 14, 2014.

  1. Steve0701

    Thread Starter New Member

    Jul 14, 2014
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    Simple question: Using the schematic, below, how can this basic window air conditioner be modified to make the fan turn on and off with the compressor, via the thermostat? It is a 2-speed fan, and if I had to choose just one speed it would be Low. I already tried removing the white wire from the switch and jumping it to the thermostat. It cooled OK, but when the thermostat opened, I could hear the fan motor buzzing quietly and trying to turn. The whole idea here is to set the thermostat and let the air conditioner start up and run when, and if, the room gets warm, all without having the fan running constantly 24/7.

    [​IMG]
     
  2. inwo

    Well-Known Member

    Nov 7, 2013
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    The red is for high and the white is for low. Only one can be connected at a time.

    Connect the white as you did before, but you must also disconnect the red. (tape it)

    Edit:
    Should have worked before when set to low.
     
    Last edited: Jul 14, 2014
  3. crutschow

    Expert

    Mar 14, 2008
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    If you wanted to maintain the high/low fan setting then you could connect the thermostat between the mains power and the switch (black wire). Remove the two red wires from the thermostat that go to the compressor and connect them together. Break the black wire between the mains and switch, and connect the thermostat in series. Leave the fan wires as originally connected.
     
  4. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,980
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    Have you removed the white fan wire from the switch,and connected it to the red compressor wire,put the switch in low cool position.
     
  5. inwo

    Well-Known Member

    Nov 7, 2013
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    +1

    There ya go.

    Why was I drawing a 2 speed switch?:cool:
     
  6. Steve0701

    Thread Starter New Member

    Jul 14, 2014
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    Thank you for the elegantly simple, perfect solution! Alas, it looks like I had already hurt the high speed motor winding by using my first solution - probably walked away with the switch on a forbidden setting. It now only runs on Low when set to High, and only after you help it with a little push. Anyway, I may try to take the motor apart to look for a blown thermal fuse. The sticker does say "thermally protected," and it has it's own schematic with a 130 degree C. see-saw icon that could be the fuse, see below.
    [​IMG]
     
  7. inwo

    Well-Known Member

    Nov 7, 2013
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    It looks like a resettable device in the common lead. If it was open motor would not try to run.

    Motors don't take kindly to both speeds connected at once.:(
     
  8. crutschow

    Expert

    Mar 14, 2008
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    If it runs but does not start, perhaps the capacitor went bad.
     
  9. Steve0701

    Thread Starter New Member

    Jul 14, 2014
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    Capacitance testing! Now I know why I should have kept an analog multi-meter. All of my cheap digitals lack a MFD setting and they are too slow to respond to a capacitor. I found the 130°C fuse inside the motor housing, and (unfortunately) it’s fine. So, I think I ought to test the motor’s electrical connections: red, white, blue, & black, but which combinations are supposed to have resistance, and which should be open? [2-speed motor, Red is High, White is Low].
     
  10. crutschow

    Expert

    Mar 14, 2008
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    In general I would think there should be continuity between all combinations of wires.
     
  11. Steve0701

    Thread Starter New Member

    Jul 14, 2014
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    Thanks for all the comments. On the positive side, I now know how to modify a window unit for Economy Mode by simply placing the thermostat in series with the hot lead as the very first component. On the minus side, my earlier experimentation destroyed the motor winding, so nothing happens on low speed, and it needs a manual push to run at reduced speed when set to high. To finish this little project, I will be cutting the thermostat out of the circuit. That way, once the fan is running, the unit can never cycle and leave the compressor running without a fan (unless the electric service blinks!). Yes, I ought to junk this unit ASAP. BTW, Frigidaire does not offer the motor through its parts network- seems awfully lame, but it is what it is.
     
  12. crutschow

    Expert

    Mar 14, 2008
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    The fan motor may be a fairly standard unit. Have you looked for a generic replacement?
     
  13. Steve0701

    Thread Starter New Member

    Jul 14, 2014
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    Ebay has about a dozen Welling motors, some look like the right shape, but no two are alike. Mine is model YSK20-6AS with a fairly long shaft and a fan on each end. Tell you what, I will look for a customer contact page and and ask Welling for something compatible.
     
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