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Thread: LMTV Air Conditioner AC Main Unit Gen1 and Gen2 Details

  1. #11
    4 Star General Keith_J's Avatar
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    Thanks OD for the prompt clarification. Yes, green to clutch is std in auto AC market. But the plug with the yellow wire doesn't mate to the switch on the dryer.

    Then there is the other plug, also with two wires, which is unknown. Sorry, I'm a bit shelled from the heat as lunch was resampled around 1530 and have been feeling quite miserable.

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    Colonel Overdrive's Avatar
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    Ok. Will look at my condenser harness in the morning. There should be the 4 pin to the condenser harness from the main unit, then a 2 pin to the dryer, and a second 2 pin that goes to the compressor. We may have a situation where there are two unknown pigtails that complete the connections to the dryer and compressor.

    If this is true I will use a couple of waterproof 2 wire generic connectors to complete the connections.
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  4. #13
    4 Star General Keith_J's Avatar
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    Nice. Looks like there is a problem with the dryer switch type as it is a binary with three pins. This keeps compressor from running if charge is low or temperature to low.

    Which means there are two switches in the system. As we have no hose kit yet, I didn't know.

    The compressor has one service port but no high pressure service port.

  5. #14
    4 Star General mkcoen's Avatar
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    Unfortunately all the pieces were sourced seperately so no telling if the condenser is a Gen1 or Gen2. The drier came with the compressor so no telling what it is either other than it has a 3 pin round connection. So the setup, other than the evaporator is not simply a "plug-and-play" combo.
    KG5RKO
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    Colonel Overdrive's Avatar
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    Let me clarify my last post... When referring to Gen1 and Gen2 I am talking about the cab main unit with the controls. I have not seen the different versions of the condenser so I don't want to call them Gen1/Gen2. Although, why not start calling them Gen2 Condensers (with the L brackets) and give mkcoen ALL the cred Based on previous posts in other threads there does seem to be a versioning of the condenser based on what we have seen with different mounting brackets. The condensers I have for the LMTV all have the little L brackets to mount them.

    The Dryer:
    Here is a pic of the dryer that comes attached to the MRAP 3 fan condensers I have. I am not suggesting that this is the proper dryer for the LMTV AC setup but it does show a 2 wire connector for the high pressure switch.
    MRAP_3Fan_Condenser001.jpg

    Now here is the secret info (being humorous here): Here is a pic of the dryer that is claimed to be the LMTV dryer on eBay. It does not come with the high pressure switch but you can see the port for it. I may snag one of these and steal the high pressure switch from the MRAP dryer I have or just use the MRAP dryer. This is my 2nd option since the dryer on the MRAP setup is a LOT smaller than the suggested "real" LMTV dryer.

    I did a little research on Red Dot dryers and I believe this may be the correct dryer for the LMTV.
    LMTV_Dryer_possibly001.jpg

    Stock Condenser Wiring:
    Here is a pic of the wire harness ends showing the two, two wire connectors for low pressure and high pressure switches and the single plug for the compressor.

    (Wire identification & operation: Keith_J - "The white two pin plug w black wires is the low pressure cutout switch. The red two pin plug with purple wires is the high pressure fan switch. How this works? Low pressure prevents operation if refrigerant charge is low or absent. This prevents oil starvation in comp. Also, it prevents evaporator icing since temp corresponds to pressure.
    High pressure switch makes fans turn on only when needed. Ram air at 58 MPH is more than needed so fans freewheeling)."

    LMTV_Condenser_harness001.jpg



    OD
    Last edited by Overdrive; 06-24-2016 at 13:41.
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    M116A3 HSTRU - Next Project
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    S-788 Shelter on a M1102 Gen Trailer
    S-805 Com Shelter on a M1102 Gen Trailer
    S-805 Com Repair Shelter with MEP-903B Gen on a M1102 Trailer
    M1102 sensor trailer waiting for another shelter project!

    SOLD - All LMTV related parts

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    mkcoen (06-24-2016)

  9. #16
    4 Star General mkcoen's Avatar
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    Isn't the single green the compressor wire?
    KG5RKO
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    1955 Austin Champ
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  10. #17
    4 Star General Keith_J's Avatar
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    Yes MKC, the single plug green wire is the comp clutch. The whitebtwo pin plug w black wires is the low pressure cutout switch. The red two pin plug with purple wires is the high pressure fan switch of which I don't know location.

    How this works? Low pressure prevents operation if refrigerant charge is low or absent. This prevents oil starvation in comp. Also, it prevents evaporator icing since temp corresponds to pressure.

    High pressure switch makes fans turn on only when needed. Ram air at 58 MPH is more than needed so fans freewheeling.

    It took 24+ hours to extinguish my helmet fire and make sense of the wiring.

    The fan over ride is handled in the main evaporator unit. I doubt the binary pressure switch could be used so we have to source the correct pressure switches. I'm not familiar with the Delphi brand sealed connectors used. Hopefully someone at the auto ac shop knows.
    Last edited by Keith_J; 06-24-2016 at 12:41. Reason: Clairification

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    Colonel Overdrive's Avatar
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    ok great info I corrected my last post as well as the big list and cited credit to Keith_J with a quote from your post as well.
    Last edited by Overdrive; 06-24-2016 at 13:39.
    M116A2 HSTRU Hydraulic Repair Trailer - Expedition Conversion (complete)
    M116A3 HSTRU - Next Project
    M720 Shelter Dolly
    S-788 Shelter on a M1102 Gen Trailer
    S-805 Com Shelter on a M1102 Gen Trailer
    S-805 Com Repair Shelter with MEP-903B Gen on a M1102 Trailer
    M1102 sensor trailer waiting for another shelter project!

    SOLD - All LMTV related parts

  12. #19
    4 Star General mkcoen's Avatar
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    Do you have the hoses for your set? Any electrical connections on it? Could there be an intermediate wiring harness that would plug in between evaporator and condenser loom?
    KG5RKO
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    1955 Austin Champ
    1980 M116A2 MEP003
    1995 M105A3

    US ARMY - Overlanding since 1775




  13. #20
    Colonel Overdrive's Avatar
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    mkcoen,
    You guys are out in front of me on the install. I have what I believe is the main return line from the evaporator to the compressor (big fat long hose). I have been playing around with how that hose routes down from the main unit to the compressor so let me know how you routed it. I have a couple of different hoses flagged and am watching on eBay but I wanted to see someone actually use them. Obviously we don't want to route those hoses anywhere near the cab tilt mechanism.

    Here is what I am assuming, and please correct me on hoses. Big hose from the red, large port on the main cab unit to the compressor then smaller line, high pressure to the condenser, then dryer then into the smaller blue port on the main cab unit.

    Where are you installing your dryer?

    On the harnesses, it is my belief that the main unit harness plugs into the condenser harness we have been talking about then it "looks like" there are a couple of pigtails that go to the high and low pressure switches. They don't seem long enough at least for the compressor close switch. The wiring diagram for Gen2 shows it plugging directly into the condenser harness with the 4 pin plug.
    M116A2 HSTRU Hydraulic Repair Trailer - Expedition Conversion (complete)
    M116A3 HSTRU - Next Project
    M720 Shelter Dolly
    S-788 Shelter on a M1102 Gen Trailer
    S-805 Com Shelter on a M1102 Gen Trailer
    S-805 Com Repair Shelter with MEP-903B Gen on a M1102 Trailer
    M1102 sensor trailer waiting for another shelter project!

    SOLD - All LMTV related parts

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