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  1. #14
    Join Date
    Jul 2007
    Location
    The Hot South
    Posts
    1,350
    Did you run the EXV test on the micro? Did you check the wiring between micro and EXV? Did you check the output out of the main base board? Some chillers have an 'amplifier' between the main base board and EXV which 'amplifies' the pulse signal. Did you check that? The test procedures are in the book.

  2. #15
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
    Posts
    2,304
    Quote Originally Posted by _knight_ View Post
    Do you happen to have a reference chart for the dcv drop that I can check the temps the thermistors are sensing while it is running?
    Download the pdf file ( 30GT-2T_1.pdf )

    Table 16 and Table 17

    Page 43

  3. #16
    Join Date
    Sep 2005
    Location
    Maryland
    Posts
    221
    Well. You guys were right, it was the sensors. They ohmed out fine, yet they were the problem. The board got delivered to me but I changed out the thermistors first, turned it on....runnin great. Thank you for all the replies, and thank you for the .pdf commtech, it was all much appreciated.

  4. #17
    Join Date
    Oct 2011
    Location
    South Georgia
    Posts
    71

    Wink

    The old Flotronics chillers with 750 step EXV were notorious for the EXV sticking due to carbon deposition in the orifice and exv spool. Cleaning them any time you have got the circuit open is a good idea. Be sure you have a new o-ring before you open up the exv. Secondly, they would stick if just a minute trace of moisture is in the refrigerant, so good dehydration and driers is a must.

    I have actually verified the voltage drop measurement at the processor and looked at the readings via flotronics monitor and found discrepencies. By this i mean flotronics monitor was showing say 55 degrees which is actually what the processor thinks it is. However the voltage dcv measurement would translate to a different value sometimes as much as ten degrees off. It is best to try and get a free copy of flotronics monitor into an old windows 98 program and use it.

    In some cases i have removed the exv,s, disabled the exv and selected txv on the processor. Installed properly sized txv's and solenoids and wired in the liquid solenoids as shown on the schematics. Basically if your schematic shows the lls wiring then you can do it. Otherwise you have to wire off of the first stage compressor contactor utilizing a time delay relay. The machine is not nearly as efficient as the cooler barrell is not quite as flooded. I converted several machines and most of them are still running years later with no compressor losses.

    Any time you are checking the superheat calculations via the sensors; try measuring the actual superheat using suction pressure and an accurate temperature probe ( do not shoot it with a laser) strapped into a well insulated section of insulation. If everything is correct you should see around 10 degrees real superheat with something like 22 degrees sensor superheat. That sometimes can tell you a lot about what is actually happening. The 06e oil sight glass should have a blue steady oil level and not be foaming. Some intermittent foaming is to be expected, but it should not be continous.

    Finally, if the job is one in which one or two air handlers have three way chill water valves these machines are slow to respond to load changes from supply water bypass . Suction line accumulators can help a lot. Personally i think all of the 30GB and 30GT series machines should have had suction accumulators.

    Just about the time that Carrier got the product line to a good reliable machine, they discontinued it. Still, they are one of the best brine chillers around.

  5. #18
    Join Date
    Sep 2005
    Location
    Maryland
    Posts
    221
    Quote Originally Posted by CCSPIERCE View Post
    The old Flotronics chillers with 750 step EXV were notorious for the EXV sticking due to carbon deposition in the orifice and exv spool. Cleaning them any time you have got the circuit open is a good idea. Be sure you have a new o-ring before you open up the exv. Secondly, they would stick if just a minute trace of moisture is in the refrigerant, so good dehydration and driers is a must.

    I have actually verified the voltage drop measurement at the processor and looked at the readings via flotronics monitor and found discrepencies. By this i mean flotronics monitor was showing say 55 degrees which is actually what the processor thinks it is. However the voltage dcv measurement would translate to a different value sometimes as much as ten degrees off. It is best to try and get a free copy of flotronics monitor into an old windows 98 program and use it.

    In some cases i have removed the exv,s, disabled the exv and selected txv on the processor. Installed properly sized txv's and solenoids and wired in the liquid solenoids as shown on the schematics. Basically if your schematic shows the lls wiring then you can do it. Otherwise you have to wire off of the first stage compressor contactor utilizing a time delay relay. The machine is not nearly as efficient as the cooler barrell is not quite as flooded. I converted several machines and most of them are still running years later with no compressor losses.

    Any time you are checking the superheat calculations via the sensors; try measuring the actual superheat using suction pressure and an accurate temperature probe ( do not shoot it with a laser) strapped into a well insulated section of insulation. If everything is correct you should see around 10 degrees real superheat with something like 22 degrees sensor superheat. That sometimes can tell you a lot about what is actually happening. The 06e oil sight glass should have a blue steady oil level and not be foaming. Some intermittent foaming is to be expected, but it should not be continous.

    Finally, if the job is one in which one or two air handlers have three way chill water valves these machines are slow to respond to load changes from supply water bypass . Suction line accumulators can help a lot. Personally i think all of the 30GB and 30GT series machines should have had suction accumulators.

    Just about the time that Carrier got the product line to a good reliable machine, they discontinued it. Still, they are one of the best brine chillers around.
    I agree with you on this, before I changed the EXV I was actually considering going to a txv with due to the price of the EXV, I also agree about the accumulator, but now that it is back up and running, I'm a happy man. Thanks for the input, much appreciated.

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