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  1. #1
    Join Date
    Feb 2007
    Posts
    14

    Troubleshooting problem with Ice Cream Display Case

    Im working on an ice cream display case. Inside the case will not cool down, only about 10% of the evaporator is getting cold (where the cap tube enters) the rest is warm to touch. There is a hissing sound where the cap tube enters and it is frosted over. My guages show the LP as 0 bar (about -40C or so for 404A) and 12 bar for the HP. The weird thing is that when I cut off the machine, the LP immediately goes up from 0 bar to 5 bar and the HP goes down, telling me, I think, that the pressures are meeting each other. I suspected an obstruction in the cap tube, but why would the pressures equalize so fast? Is this superheat pushing down the suction valve? I also suspected bad compressor valves (hermetic), but what about the problem with the evaporator, would this be a symptom of bad valves? Also, I noticed that the suction access valve tube was warm to touch, but Im getting 0 bar, and doesnt that correspond to a low temp.? How could the guage be reading 0 bar with a warm access tube? Shouldnt the tube be cold? Thanks for any help!

  2. #2
    Join Date
    Jan 2006
    Location
    DFW Metroplex
    Posts
    4,910
    I haven't been around much in the last couple of months..........but my memory isn't THAT short.

    http://hvac-talk.com/vbb/showpost.ph...3&postcount=32

    Good luck

  3. #3
    Join Date
    May 2007
    Location
    maryland, baltimore
    Posts
    135
    sounds like compressor is bad either valves are warped or pressure is blowing by the piston. Try to pump down the unit and see if it holds. Motor has probably overheated more than once.

  4. #4
    Join Date
    Jul 2007
    Location
    N.C.
    Posts
    702
    Call a qualified tech. Sounds like you want a cheap fix and you still are getting what you pay for. Any one with the proper knowledge would see obvious problems with the very limited info you gave.

  5. #5
    Join Date
    Feb 2007
    Posts
    14
    I see we are still playing the same games we were playing a year ago. I went and tried to find a new company to learn at, and unfortuantley Ive had to figure out allot on my own as we are understaffed. Nobody else at the company can figure it out. I came here to ask a question in a respectful way but there always seems to be two duechbags that gave me the usual run around. For the guy that tried to help, thanks. The problem is I cant do a pumpdown because the compressor is hermetic and the access valves are schrader valves, not service valves.
    For the duechbag that said the answer was simple and I should know, why didnt you post the answer?

  6. #6
    Being young and not able to contribute too much, I would do this. If the case is small enough to load up, take it back to your shop where you can work on it and maybe have some help. Open the system, check for a restriction, maybe the comp is bad, do some investigation under a nonstressfull enviorment, I know you'll learn something.

  7. #7
    Join Date
    Jan 2006
    Location
    DFW Metroplex
    Posts
    4,910
    Quote Originally Posted by raider94 View Post
    For the duechbag that said the answer was simple and I should know, why didnt you post the answer?
    I don't suspect it would have anything to do with fact that your attitude SUCKS...........do you?

    And what's with the name calling?

  8. #8
    Join Date
    Feb 2007
    Posts
    14
    Geez, some advice. I guess I came here looking for some alternative answers but I think I ended up answering my own question in my first post. When the guage is closed and machine is stopped, the pressures should not immediately equalize unless valves arent sealing. I cant change out a valve plate because the compressor is not a semi hermetic and a cap tube replacement might be out of the question as well, depends on what the customer will pay for. I was going to cut out the cap tube and then weld a new one in, but I suspect the compressor.

  9. #9
    Join Date
    Feb 2007
    Posts
    14
    As far as the "name calling" Im sure they can deal with it as its surely not the first time they have been called a duechbag. Unfortuantely, there are lots of these types out there, you know the ones, that just get in the way when your trying to get that answer. All Im looking for is the solution, to get to that next level. Im sure duechbag will give me a long lecture on how Ill never get to that level by acting like this! But when you ask duechbag a question, he dances around and acts like he has a monopoly on all the knowledge. Im getting too old for duechbag and his games. I ask a question in a civil manner, and if I get a reasonable response, I thank him or her for what their effort. If I get what you saw here, I will respond as you see. I always feel better about the situation, and duechbag gets offended. Works for me.

  10. #10
    Join Date
    Nov 2005
    Posts
    385
    I agree with markettech YOUR ATTITUDE SUCKS move on. you sound like a little baby waw waw.

  11. #11
    Join Date
    Jul 2008
    Location
    Denver, CO
    Posts
    4,203
    Quote Originally Posted by raider94 View Post
    Geez, some advice. I guess I came here looking for some alternative answers but I think I ended up answering my own question in my first post. When the guage is closed and machine is stopped, the pressures should not immediately equalize unless valves arent sealing. I cant change out a valve plate because the compressor is not a semi hermetic and a cap tube replacement might be out of the question as well, depends on what the customer will pay for. I was going to cut out the cap tube and then weld a new one in, but I suspect the compressor.
    I wouldn't go messing with the captube thats something for an experienced tech. I would start by recovering the refrigerant and way the bottle to see how much you pull out then run nitrogen through the system and see if it blows clear through, then pull the system down to a 15 micron vaccume for a 1/2 hour then recharge the system with the ammount on the name plate and see what happens

  12. #12
    Join Date
    Feb 2007
    Posts
    14
    Ive already pulled a vaccum, it sat in the corner for weeks with guages on it and held the vaccum. If the machine held the vaccum, then I dont see any need to pressure test with nitrogen. The machine is not leaking. The machine has been charged, recovered, vaccumed charged, leak checked many times. Why should I pull out the gas again? I guess I could see if it will blow nitrogen through the system, thats something I considered. Alsos, why is replacing the cap. tube such a complicated task? Ive already replaced several on other machines. I dont think its the cap tube, probally the compressor. Just curious, but are you people really all that good? I see allot here about your attitude sucks or call an experienced tech. but the advice Im getting here isnt all that great.

  13. #13
    Join Date
    Jun 2008
    Location
    South Carolina
    Posts
    36
    Replacing the cap tube may not be hard but, installing the correct size and length can be a pain. Its real important to have the correct one. With your system equalizing so quickly, I would guess that your compressor is bad.

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