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  1. #1
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    May 2019
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    Question Need advice/pointers on a Trans/Air bus unit

    I've got a '99 Blue Bird bus with a Trans/Air split AC unit in it and I'm wondering who might have some advice for me on operating it from an electric motor instead of the engine. It uses two Delco A6 compressors, each driven with its own V-belt from the engine. I haven't been able to follow all of the lines. A sticker on the engine says that the system takes 9lb14oz of R-134. I haven't been able to find a placard yet with a BTU rating, or any other useful information (except that it allegedly takes 10oz of PAG.) Typical service ports are located on the lines near one compressor.

    I'd like to be able to run this unit from an electric motor while stationary. Is that just impossible? I am increasing the insulation of the vehicle, so I probably do not require the full cooling capacity. If I ran just one compressor, would the system likely develop working pressure? I am familiar with A/C concepts, but have no experience - I have an ASE A-7, but have never actually worked in the industry.

    I would be grateful for any guidance. Thanks.

  2. #2
    Join Date
    Apr 2003
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    St. Louis
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    https://www.hemmings.com/blog/articl...ng-compressor/
    Have no idea how to incorporate two clutches one for a motor and one for the engine and fitting a sizable motor the ran the compressor let alone the fan motors for the condenser and evaporator. Roof top electric units and a generator a lot easier.

  3. #3
    Join Date
    May 2019
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    California
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    Thread Starter
    Quote Originally Posted by servicefitter View Post
    Have no idea how to incorporate two clutches one for a motor and one for the engine and fitting a sizable motor the ran the compressor let alone the fan motors for the condenser and evaporator. Roof top electric units and a generator a lot easier.
    I'm not worried about dual clutches, I can just switch the belt over. That's an annoyance, but not a big deal.

  4. #4
    Join Date
    Jan 2004
    Location
    PA
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    How many batteries will you have for it to run on/ or how many amp hour is the battery they will run on?

    Each compressor will be about 3 HP, perhaps as high as 4 HP each. So they will be a high power draw on a battery.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  5. #5
    Join Date
    Apr 2010
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    California
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    Quote Originally Posted by hyperlogos View Post
    I've got a '99 Blue Bird bus with a Trans/Air split AC unit in it and I'm wondering who might have some advice for me on operating it from an electric motor instead of the engine. It uses two Delco A6 compressors, each driven with its own V-belt from the engine. I haven't been able to follow all of the lines. A sticker on the engine says that the system takes 9lb14oz of R-134. I haven't been able to find a placard yet with a BTU rating, or any other useful information (except that it allegedly takes 10oz of PAG.) Typical service ports are located on the lines near one compressor.

    I'd like to be able to run this unit from an electric motor while stationary. Is that just impossible? I am increasing the insulation of the vehicle, so I probably do not require the full cooling capacity. If I ran just one compressor, would the system likely develop working pressure? I am familiar with A/C concepts, but have no experience - I have an ASE A-7, but have never actually worked in the industry.

    I would be grateful for any guidance. Thanks.
    Hello, and Welcome. To get right to it, "Not Impossible to do", and "Yes, it Can Be Done". Now, my question to You, is Why do you want to do it? In other words, what is your motivation, ie.repurposing the 2 A-6 Compressors for Fun or Money Savings or Other? Are You trying to design and build a package hvac unit for your own purposes? I ask you this, because when you start down this modification and re-design road, the $$$ can add up very quickly. If you still wish to go forward with it, stick around, and I will return with a list of possible Pitfalls and Costs. Good Luck !

  6. #6
    Join Date
    May 2019
    Location
    California
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    10
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    Thread Starter
    The bus has this AC already, and it has a contoured enclosure which matches the interior, so I'm trying to retain it. I hate to add another unit IF I could spend the money just driving the existing system. I don't need it to run off battery much, just solar while the sun is shining, and panels are cheap. On the other hand, I would be hard-pressed to get more than about 1500W of panels up there due to vehicle length, so it sounds like I can't really produce enough power to run even one compressor...

  7. #7
    Join Date
    Apr 2010
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    California
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    Quote Originally Posted by hyperlogos View Post
    The bus has this AC already, and it has a contoured enclosure which matches the interior, so I'm trying to retain it. I hate to add another unit IF I could spend the money just driving the existing system. I don't need it to run off battery much, just solar while the sun is shining, and panels are cheap. On the other hand, I would be hard-pressed to get more than about 1500W of panels up there due to vehicle length, so it sounds like I can't really produce enough power to run even one compressor...
    Keep in mind, that this electric motor will NOT run off the solar panels, but will run off a very large battery/batteries. The Solar panel will then attempt to re-charge the batteries at an acceptable rate. Also, if you use an A/C drive motor, you will then need to add an inverter. So, let me ask you this, do you have an old bus with a dead engine in it, and then want to live in it, and modify the 2 engine drive compressors to cool it? I'm a little fuzzy on this deal so hep me to understand it please.

  8. #8
    Join Date
    May 2019
    Location
    California
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    Thread Starter
    No, it's a living bus that's being converted into an RV. I'd like to have the use of the AC while on the road, AND while parked (without running the engine.) I can't possibly run both compressors without doing slide-out solar panels etc. Can I run just one compressor or will that likely not produce sufficient pressure for operation? Probably I'd be best off just pulling this unit and replacing it with two smaller units, but I'd love to be able to use what's there.

  9. #9
    Join Date
    May 2019
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    I don't need it to run off battery much, just solar while the sun is shining, and panels are cheap.
    Panels are cheap? What state are you from?
    And how many panels do you get for what appox. price? So I will try to figure it out.

  10. #10
    Join Date
    Apr 2010
    Location
    California
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    Quote Originally Posted by hyperlogos View Post
    No, it's a living bus that's being converted into an RV. I'd like to have the use of the AC while on the road, AND while parked (without running the engine.) I can't possibly run both compressors without doing slide-out solar panels etc. Can I run just one compressor or will that likely not produce sufficient pressure for operation? Probably I'd be best off just pulling this unit and replacing it with two smaller units, but I'd love to be able to use what's there.
    What is the length and width of your bus? Photos are great if you can add. PS: Solar Panels are no more than trickle chargers...Do you Agree? PSS: Gotta go now but please stick around!

  11. #11
    Join Date
    Apr 2010
    Location
    California
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    Ok, So You want to continue to use your 2 present engine driven A-6 Compressors, existing evaporator, condenser, lines etc. and modify the mount and drive brackets to allow them to be driven "Electrically ONLY", is that Correct?

  12. #12
    Join Date
    May 2019
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    California
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    Thread Starter

    I haven't just gone away

    I went and took a photo. But now I see I'm not allowed to upload them?

  13. #13
    Join Date
    Nov 2006
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    Southeastern Pa
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    You need a couple more posts to be able to upload pictures.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist
    Member, IAEI

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