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Refrigerator relay pinout

Discussion in 'Electronic Repair' started by Edu, Jun 19, 2006.

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  1. Edu

    Edu Guest


    I am trying to start a refrigerator compressor with a burnt relay, with
    a new one, but the one I bought is a generic relay, and the pinout is
    not the same as the original one.

    The new one is this:

    As you can see, the are two boxes. The white one has an overload
    protector inside. The are two "real" pins. The black box (relay) has 3
    pins, and pin 1 comes tied to a spare hole in the overload protector, I
    think that expecting me to wire it to a real pin.

    I don't know how to feed it. I tried powering one of the pins in the
    protector with 220v, the other pin of the protector to pin 1 of relay,
    and then pins 2 & 3 of the relay to run & start in the compressor, but
    the compressor start winding burnt. I have another compressor the test,
    but no more...

    Any help would be appreciatted.

    Thanks in advance!
  2. Edu

    Edu Guest

    Please, I need help on this. Have you ever seen a relay like this? Who
    can tell me the pinout for this???

  3. CJT

    CJT Guest

    The vendor you bought it from should be able to provide the pinout.
    As an alternative, you could probably use a multimeter to determine it.
  4. lsmartino

    lsmartino Guest

    Edu ha escrito:
    You are completely wrong. The white box IS the relay, and the black
    circular piece is the overload protector. You have to connect one of
    the two incoming wires to the remaining terminal of the overload (the
    black circular piece), and the remaining wire to the relay, which is
    the white box. The relay must be plugged in the compressor. The
    compressor has three pins and the RELAY (remember, the white box)
    should have three holes to plug it directly to the compressor.

    One the 4 external contacts of the relay should be marked as common.
    That´s the one you will use to connect the remaining power wire. The
    other three contacts are provided in case you need to use a run
    capacitor, a start capacitor or both. If your compressor doesn´t need
    a cap, you just leave these contacts unused. If the common terminal
    isn´t marked, or the relay kit didn´t came with an electrical
    schematic, you should determine which one is common with a DMM.

    Again: the relay is the white box, and the circular black piece is the
    overload protector.

    If all this sounds like japanese to you, or you don´t know how to use
    a DMM, look for a refrigeration technician.

    The other pins of the relay are provided to connect an startup
    capacitor, a run cap, or both, in case the compressor needs them.
  5. Edu

    Edu Guest

    Hi, thanks for the reply!

    I'm not completly sure the relay is the white box. I disassembled it
    and there was only a ceramic disc, what I assume to be an overload
    protection. There are only two real contacts inside, one at each side
    of the ceramic disc. But each contact goes out by two pins each. So, I
    have 4 pins, 2 of them wired to one side of the disc, and the other 2
    wired to the other side of the disc.

    The black box is sealed. Pin 1 is wired to, but not connected to, an
    empty hole in the white box, as expecting to be jumpered to one of the
    4 pins in it. Pin 2 and 3 are ready to connect to "something", but pin
    3 is different, smaller than the other.

    I have electronics and electric knowledge. I have tested both, and I
    get almost 0-ohm between every pair of pins in the black box, and 0 ohm
    between both sides of the white box.

    Any idea??? Im completly lost!


    lsmartino ha escrito:
  6. lsmartino

    lsmartino Guest

    Edu ha escrito:
    This is because the "relay" is a PTC, used to provide a momentary pulse
    to the starting windings of the compressor. As soon the PTC "relay"
    heats, it resistance increases and the voltage applied to the starting
    winding is vastly reduced. It operates under the same concept as a PTC
    for the degaussing coil inside a TV. The PTC relay is a substitute for
    the electromagnetical relay in modern compressors.

    Google for "Tecumseh" and have a look at the starting circuits of some
    compressors. That should give you an idea about what to do with the
    starting kit you have.

    And again, the black box IS an overload.
  7. Edu

    Edu Guest

    Ok, thanks for your time. Now I think I understand everything!
    So, I have to wire the white box (relay) between run and start, and
    apply 220v to common and run, placing in series the overload protection
    (black box).

    As the overload protection has 3 pins, I assume pins 1 & 2 are the
    "in/out" pins, and the 3rd pin, which is a thinner faston, is for some
    add-on line start or run capacitor. The original relay didn't have any
    capacitor, so maybe I can left pin 3 unconnected.

    Am I right??? I can see the light at the end...:)

    Thanks a lot!


    lsmartino ha escrito:
  8. lsmartino

    lsmartino Guest

    Edu ha escrito:
    The overload protection has only TWO contacts. The center screw is for
    adjusting the overload protector at factory, its NOT a connection pin
    to anything.

    Remember that the PTC relay should be plugged directly to the
    compressor. In one of the sides of the relay, there should be three
    holes. Align these holes with the three compressor pins, and plug the
    PTC relay there.

    This is a schematic from a refrigeration compressor. In the page two
    you will find a wiring diagram:
  9. Edu

    Edu Guest

    Well, actually the overload has 3 real pins, none of them is a screw,
    but it is true that the one numbered "3" is a half-width faston, while
    1 & 2 are normal fastons.

    The relay has 2 real faston plugs at one side (both to the same side of
    the PTC), and at the other side I think there are 4 small holes which
    might plug directly to 2 pins from the compressor (start/run). Maybe
    the spare wire which comes from the overlad to an empty hole in the
    relay is intended to make it match the position of the "common pin" in
    the compressor (see photo I attached, altough it is right in the
    opposite side, at the end of the black wire).

    This weekend I will to to make the last compressor I have alive run...
    I hope everything works! Your should have seen the wiring I made at my
    first attempt ! It has changed a lot since your help ..!! :)

    Thanks a lot for your time!

    Best regards!

    lsmartino ha escrito:
  10. lsmartino

    lsmartino Guest

    Edu ha escrito:
    This sounds right. That way the overload will get connected to the
    common pin of the compressor, thus protecting both the start and run

    Good luck then!
  11. Edu

    Edu Guest

    Hi again!

    Could you believe the relay fitted directly into my compressor! The
    opposite side from the side seen in the picture I took, has both
    start/run plugs in the neccessary size, and the spare wire coming into
    a hole from the overload protector was, as we supposed, directly
    plugged in the common pin. I was making difficult the easy things.

    Now the compressor works perfectly. The only thing I have noticed is
    the stop time I must allow between stopping and starting again. I have
    read somewhere about the time the PTC needs to cool again. I don't
    think it would be a problem (the compressor is not intended for a
    fridge, I will boild an air compressor with a fire extinguisher as a

    Thanks for opening my eyes, and best regards!

    lsmartino ha escrito:
  12. lsmartino

    lsmartino Guest

    Edu ha escrito:
    I believe you because that was exactly what I tried to tell you in the
    previous posts. Maybe we could communicate better if we used Spanish in
    the the first place. :)
    Exactly, the PTC needs to cool down in order to work again. Is exactly
    the same thing which happens in a TV with the degauss thermistor.
    I´m glad to see that you could complete your project. Next time you
    have to replace a realya like that in a freezer, you will know what to
  13. Edu

    Edu Guest

    Are you Spanish too??? :)
    Well, my complete project is an air compressor. I still have to find
    some other components and make practise in copper soldering...
    The person who gave me the compressor for free from an old
    refrigerator, has just asked me about repairing his kitchen
    refrigerator, which has just stopped cooling. Now I have more
    information about it. Some weeks ago I though the compressor was a
    three-phase motor started with 1 phase and a starter capacitor...:)
    And many other things I have learned surfing the web these days in
    search for more info (about nofrosts systems, for example).

    Thanks again, and best regards!
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