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  1. #1
    Join Date
    Aug 2013
    Location
    Omaha
    Posts
    551

    Hobart Cooler....I know I got this right...did I?

    K, hobart 8 door. (pass thru style 4 half doors on each side). complaint...won't go below 45.
    Found compressor to be weak. R12 suction won't go below 30 and head is 90 in a 85 ambient. Condenser looked like sh*t so I recommended replacing the condensing unit as a whole...
    original: JRE1-0033-Iaa.... crossed over to a condensing unit with this comp: ARE37C3E-IAA

    So, installed new condensing unit with new cap tube and left. called back won't go below 43. check it out, found I was a clown and did my calculation for the cap tube wrong... I installed 79" of 0.042. The new comp has 2170BTUS at 20F evap so according to tecumseh's box load program I actually needed only 64" of 0.042.

    BEFORE i changed the tube with the box @ 45 I had 15 suction 150 head...cool drier 134a.
    After...I have 22 suction 145 head..warm drier box at 50....with box at 40 I had 19 suction 145 head...drier not as warm. I called it good and left.
    I installed a new A12-700 when i did the condensing unit.

    Called back...won't go below 41. Bout to get steamed. This place is an hour away from omaha...all doors are shut and seal good..box is in great condition. Could there be something i missed??
    The condensing unit is the right size yes? I ask cuz it still takes a while to pull down in temp with nothing in the box

  2. #2
    Join Date
    Aug 2013
    Location
    Omaha
    Posts
    551
    which also brings me to another ?
    Should i have given the age of the box as a factor and maybe used a larger condensing unit?

  3. #3
    Join Date
    Jun 2009
    Location
    DFW, TX
    Posts
    661
    Box may have been designed to run at 45*f being so old. Maybe that's why it only used a 1/3hp. I would have gone back with a 1/2hp preferably with receiver, and a TXV.

    The compressor you got is a 1/3hp just like original.

  4. #4
    Join Date
    Apr 2013
    Location
    SE Nebraska
    Posts
    225
    Why did you opt out of txv? Also did you size cap tube for r12 on accident?

  5. #5
    Join Date
    Apr 2013
    Location
    SE Nebraska
    Posts
    225
    Also 1/3hp r12 has more capacity than the same using 134a.... I believe.

  6. #6
    Join Date
    Apr 2003
    Location
    Maple Grove, MN
    Posts
    1,269
    Does it get down to temperature while you're there staring at it? Does the compressor stay running? Is their thermometer reading correctly? Are they loading it up with hot food? Does it have a defrost clock that is going into defrost for an hour right before they look at it and call you? Does your new condensing unit have a receiver on it when it shouldn't?

    These small systems can be frustrating and time consuming sometimes, but you shouldn't be in a habit of leaving before the unit comes down to temperature. If it's taking a long time and you need to leave, try to return later that day or first thing in the morning to double check on it. If it is a place that is an hour away, just suck it up and stay there until you're sure it's good.

  7. #7
    Join Date
    Sep 2002
    Location
    Virginia
    Posts
    3,143
    EDIT ..... ( I was thinking A12 - 701 )

    give it another squirt of 134

    19 psi at 40 isnt far off, but it still has to get down to 32 deg which is a long haul still. Your thermostat is kicking out because the coil is too cold.

    You will have to babysit this , and watch it , and yes I hate doing it

    Put stat on 5 , and watch your suction , as is creeps down towards 36 deg , give it a squirt if pressure drops below 17

    How old is your gauge ? Make sure its fairly new to be accurate , this could be part of your issue

    Also , did you stitch the probe through the coil a few times ? I like to get a couple feet in there wrapped good

    BUT , seeing how you have a A12 -700 , Im not sure what pressures you want to watch for , never installed one that cold
    Last edited by Snapperhead; 08-08-2014 at 06:55 AM.

  8. #8
    Join Date
    Aug 2013
    Location
    Omaha
    Posts
    551
    Nope...new tube was sized for 134a..... New unit doesn't have receiver....I wanted to ditch the cap tube and retrofit to a txv but I was cockblocked and boss told me to stick with the cap tube.

    Weird thing...the old unit was controlling temp thru a low pres control..?? Is that possible with a cap tube? I've always been told u can't do that unless its a static coil.
    And @snapperhead we've always used a12700 we never use the 701

  9. #9
    Join Date
    Aug 2002
    Location
    Southold.calm
    Posts
    5,536
    Call Hobart with Mod & Ser #’s and find out what pump was on there from the factory.
    1/3HP on 4 door Pass thru?
    I just rebuilt a Traulsen 2 door that had a 1/3 HP and replaced it with a ½HP and X-Valve.

  10. #10
    Join Date
    Jun 2009
    Location
    DFW, TX
    Posts
    661
    I just worked on Traulsen passthru with 8 half doors and it had a 1/2hp :shrug:

  11. #11
    Join Date
    Feb 2004
    Location
    Madison, WI
    Posts
    290
    I read in an early post about there being an A12-700 controlling temperature, but then I read where you stated it was being controlled by a low pressure control. If it is being controlled by LP control take it out and use coil sensing a12-700. You should get better results. I've never heard of a LP control on a cap tube system and doubt it would work very well.

  12. #12
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,308
    According to Hobart's current spec sheet a two-section pass-thru with 4 half doors each side would have a load of 2240 Btuh a20°F evap temp and 90°F ambient. It also calls for a 1/3 HP unit.

    https://my.hobartcorp.com/resourcece...utmk=211870359

    The cap tube selection looks good. Did you use attach the cap tube to the suction for heat exchange or no? Did you account for the heat exchange length in the selection?

    The pressures look good. How about the superheat at the coil and the compressor. That would help too, but I'd say the unit and cap are OK. It's probably box related.

    Double check the doors. I had a couple of those pass through cooler that had what looked like minor air leaks in one or two doors. Fixing those got the box to temp OK...not great, but OK nionetheless.

  13. #13
    Join Date
    Sep 2002
    Location
    Virginia
    Posts
    3,143
    Ive never used a 700 , largely because never needed a cooler averaging 34 degrees , brrrrrr

    What low side pressure would you look for using 700 ?

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