Sudden loss of power to Carrier Supra 650 reefer unit.

Discussion in 'Refrigerated Trucking Forum' started by prsteve, Jan 21, 2021.

  1. prsteve

    prsteve Bobtail Member

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    Jan 21, 2021
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    Hello everybody!

    I have a 2013 Frieghtliner M2 with a Thermo King box and 2013 Supra 650 reefer unit. I bought the truck in early 2020 and didn't run the unit very much, but when I did it worked just fine. I'm not familiar with this particular unit and the documentation doesn't help me out with my problem. Which is...

    A couple of weeks ago I needed to run the reefer overnight to keep an early morning delivery's cargo from freezing (it was 10 or 15 deg F outside). The unit fired up, I put it in Auto Start/Stop mode, I waited until it was at temp just to be sure, then went home for the night. It ran off diesel and batteries since we don't have a standby electrical connection.

    When my driver arrived in the morning the reefer was off and, more importantly, there was no power to the control unit at all. Flicking power button on/off didn't do anything. I checked the battery connections and they are fine. I pulled every fuse in both the unit and the truck, all fine. There's no hidden inline fuse anywhere that I could see. We've run the truck a lot since then and no change in situation.

    Anybody have any ideas what I can check? Having someone experienced getting into this first hand will kill an entire day of truck + driver (we're pretty remote), so trying to avoid that.

    Thanks,

    Steve
     
    Last edited: Jan 21, 2021
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  3. reeferwrencher

    reeferwrencher Light Load Member

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    Check for power and ground at the board also check for power on the manual on/off switch in the back of the electrical box
     
    062 Thanks this.
  4. prsteve

    prsteve Bobtail Member

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    Jan 21, 2021
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    Thanks for the quick response. I haven't had a chance to test the ground yet, but for sure power is getting to the main 80A breaker. I've also not been able to check out the RSS (Run/Stop Switch) at the back of the box. It's single digit temps with 20mph winds this weekend, so not the best time to be playing around with this stuff!

    Question. Why would the RSS not be in the ON position? For sure nobody has touched it and for sure it was in the ON position when I left the unit to run overnight. The switch doesn't appear to be a type that would change its position on its own accord, so is it even possible that it switched itself to OFF?

    Thanks!

    Steve
     
  5. prsteve

    prsteve Bobtail Member

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    Jan 21, 2021
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    Follow up question. Where does the Supra's cab control unit get its power from? I don't see anything about it in either manual that I have, nor do I see it on the wiring schematic. I assume it's getting power through the dash wire harness, not from the Supra's control box. Since the symptom I'm seeing is no power to the cab control, where it gets the power from is probably an important step in troubleshooting.

    Steve
     
  6. reeferwrencher

    reeferwrencher Light Load Member

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    Highly unlikely the switch got turned off but it might be corroded and finally stopped allowing current through.I believe a 2013 would get power for the cab control from the board,but I'm not 100 percent sure about that as the older supra controllers did use to have a separate source of power such as truck fuse panel or directly from the battery.
     
  7. prsteve

    prsteve Bobtail Member

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    Jan 21, 2021
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    Thanks for that. OK, I'll double check the switch (corrosion in my climate is a possibility) and see if I can narrow down where the controls get the power from.

    In my unprofessional, inexperienced thinking I'm hoping to find a blown fuse somewhere that I've overlooked. The other possibility in my mind is something on the board blew. As soon as the weather calms down I'll poke around some more.

    Steve
     
    reeferwrencher Thanks this.
  8. prsteve

    prsteve Bobtail Member

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    Jan 21, 2021
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    Following up with the answer to my question. I had it looked at by a Carrier shop and they said the wiring harness was "melted" and the board in the reefer unit was damaged. The latter must have been on the backside somewhere as I did not notice any damage on the frontside. They had no opinion as to what might have caused the issue. Parts are on order but I won't have a chance to get it back into the shop for a couple of weeks.

    Thanks reeferwrencher for helping me confirm that a trip to the shop was a good idea.

    Steve
     
    reeferwrencher Thanks this.
  9. prsteve

    prsteve Bobtail Member

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    Jan 21, 2021
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    One last post. A warning to all you reefer newbies working with a used unit. Might want to check the weather seals on the casing and doors. One of our seals failed and corrosion built up over time where the wire harness connects to the main board. Then one day it arced taking out the main board, the control unit, and melting the wire harness. Looking at $4000 for parts and 1.5 days of labor. Totally preventable had someone (us or prior owners) noticed it.

    Steve
     
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