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  • T40 Blast Chiller not running properly

    Posted by olivero on July 28, 2020 at 10:15 am

    Hey Guys.

    Got my T40 Delfield Blast Chiller giving me some trouble. It’s a 404A semi hermetic compressor (Model is: 3DB3F33KE-TFC)
    Condensing unit is Trenton, Model#: W075L6-IT3A-3166
    TXV is this one https://www.skh-kaeltetechnik.de/Exp…without-Nozzle

    First indicator was short cycling, I happened to be walking by it and heard it go on and off repeatedly, I then went to check it out and here’s what I got.

    Unit’s running, Sight Glass is full, I don’t see any rivering, flashing or anything.
    Oil sight glass remains clear, I can see 3/4 of it is full and there’s no foaming or anything.

    When I was checking it, I had it set to run to 38*F and then shut off, one of it’s settings, from my prior checks, it runs about 15-20 PSI suction over 227 PSIG head

    Today it was running 5-8 PSI (-32.9*F Evaporating) over 337 PSI (125.8*F Condensing) SLT: 74.5*F this was after it ran for 5-10 minutes, which is way low head and way too high head, LLT is 217*F. S

    Now, here’s what scared me. 107*F superheat.

    Sounds really bad to me.

    My first thought is a restriction, I didn’t feel a signifcant temp difference on the filter drier so I’m thinking it’s the TXV, when the unit shuts off the pressure stays so it’s not leaking by on the valves or the solenoid valve.

    I was going to take the performance chart and check amps to see but my first thought is TXV. There’s no pressure tap at the txv so I can’t check SH at the evap.

    Either the Drier is partially plugged or the TXV is shot, TXV is about $1000 so I really hope it’s not that.

    What do you guys think?

    fixbear replied 3 years, 7 months ago 3 Members · 41 Replies
  • 41 Replies
  • fixbear

    Member
    July 28, 2020 at 7:53 pm

    First thing to check is why the high head. Air or water condenser? If air cooled, It should be no higher than 15F above ambient at the discharge of the condenser. How near full load is the compressor? Does it have a head pressure control? Have you checked for magnetic pull on the solenoid valve?

    The compressor is obviously getting gas due to the high head. But is it cool enough liquid to properly meter.

    Now if you can get it short cycling again, is it the high pressure switch (head) or the low pressure cutout tripping?

    Also, check the hot gas cycling solenoid (defrost) to be leaking or open.

  • fixbear

    Member
    July 28, 2020 at 8:11 pm

    I forgot to ask you if the compressor has the modulating valve on it. The Copeland Discus units can modulate from 10% capacity to 100%. It’s on top of the head.

  • fixbear

    Member
    July 28, 2020 at 8:34 pm

    I forgot to mention that this compressor has a low oil safety. Make sure you can see oil in the crankcase sight glass.

  • olivero

    Member
    July 28, 2020 at 9:13 pm

    Fixbear,

    Water condenser is what’s used. Split between inlet and outlet is 2*F on the loop, seems to be between 2-6*F on all the units we have, I checked the other ones for comparison.

    It’s cutting out on low side I would think, but I could be wrong.

    I pulled the charge today, cleaned the inlet strainer on the TXV and pulled the drier, had some trouble getting a new one but I could blow right through that drier with no problems, so I don’t think that was the problem.

    Equalizer tube is not obstructed, liquid line seems unobstructed but I haven’t been able to get the TXV to do much with the bulb in my hand, it seems as if the problem was prior to the TXV, like it’s not getting a full column of liquid.

    My SH as the evap was around 80* and at the compressor was over 100* so the evap is definetley starved.

    I’m thinking it might have been the TXV orifice screen being 30-40% plugged from what I saw, it’s so small I imagine it makes a difference.

    I see oil in the sight glass, that’s not a problem.

  • olivero

    Member
    July 28, 2020 at 9:13 pm

    I also checked the defrost solenoid and the pump down solenoid and they both work and neither leak so those are fine as well.

  • ShawnF

    Member
    July 29, 2020 at 2:18 am


    Check the evaporator coil and remove the TXV’s sensing bulb from the suction line. Check the subcooling, superheat and pressures again. If there’s no change, that’s a further indication of a TXV problem. Another test is to put the sensing bulb in ice water and checking the pressures superheat, and subcooling again

    • olivero

      Member
      July 29, 2020 at 9:19 am

      Good point, I tried holding the TXV bulb in my hand and it didn’t seem to change much, but I figure that might be because it’s already wide open trying to feed but it’s not getting liquid.

      I like the idea of the ice water on the bulb, I’ll give that a shot.

  • olivero

    Member
    July 29, 2020 at 10:40 am

    Fired it back up with the same drier since I was curious of it was actually plugged, just for my own sake.

    I got less than a 1 PSI drop through it and I’m seeing the same numbers I were before.

    3 PSI suction, SLT is 80*F and superheat is over 100*
    284 Liquid, LLT is 98*F and subcool is 15*

    So, somethings restricted, my money’s on the TXV at this point.

  • fixbear

    Member
    July 29, 2020 at 10:42 am

    Electronic cold spray works better for freezers.

    What make and model TXV does it have? Does it have a bypass tube? What charge is on it? And last, with a 33,000 BTU unit, There has to be a distributor head and several feed tubes into the evaporator. Inside that distributor there is a orifice before the cone. I assume this has a remote condenser. What size liquid line and how long. Is it possible that it got damaged?

    • fixbear

      Member
      July 29, 2020 at 10:47 am

      Oh, and has there ever been a burn up? Or multiple additions of refrigerant/oil in the past?

      • olivero

        Member
        July 29, 2020 at 11:08 am

        I believe it.

        It’s an ALCO TIE SW, 800 552. 404A unit in case I had not mentioned it.

        It’s externally equalized.

      • olivero

        Member
        July 29, 2020 at 11:10 am

        Never a burnout, I added some refrigerant 2-3 years ago after finding and fixing a leak on the liquid service valve.

        Lineset is probably 100′ or more, I don’t know how anyone would’ve damaged it, I doubt that’s the case.

        It’s a direct feed, there’s no distributor, just the outlet of the TXV going into a split tube for the evaporator, tees off the bottom and goes 2 directions.

  • fixbear

    Member
    July 29, 2020 at 12:47 pm

    It’s a direct feed, there’s no distributor, just the outlet of the TXV
    going into a split tube for the evaporator, tees off the bottom and goes
    2 directions.

    Interesting. a old way of flooded eveporator system.

    In that case, you have a orifice on the inlet of the valve.

    Your valve is not a standard, but a 800534 orifice/strainer should work ok . The charge is a SW liquid because they have a hot gas defrost. Liquid charges are very fast acting vs. gas charge. But they can not be made with maximum pressure limiting. There fore be very careful adjusting it. I ruined a 12 hp compressor some years ago flooding it due to this same type of problem. A bad charge that I couldn’t get a Sporland “Z” charge replacement and used a regular. Problem was that the valve was cranked open during troubleshooting and when the new charge was installed it flooded so quick I couldn’t stop it.

    Alco uses a very small diaphragm on their charges. So if it has lost any liquid, It will not open the valve at all. I’d be looking at that as the number one problem.

    If your interested, here is the Data Sheet for your TXV

    • olivero

      Member
      July 29, 2020 at 1:43 pm

      Thank you Fixbear,

      I spoke to Sporlan and we were able to get one made up from their parts.

      Power head will be: KT43SZ

      Cartridge is a BQC-B (1 1/4 – 2 Ton)

      Body is an EBQE with external equalizer.

      I spoke to Delfield and they said it’s probably the TXV.

  • olivero

    Member
    July 30, 2020 at 1:40 pm

    Replaced the TXV, same problem if not worse.

    Keeps cutting out at 1 PSI on the low side, high side over 300 PSI.

    Took the solenoid valve apart, clear as day, pulled the diapraghm just to be sure, didn’t change a thing.

    I can hear the TXV whistling or whatever it’s called.

    What else could it be? Pulling my hair out here.

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