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Thread: RTAA screaming

  1. #1
    Join Date
    Dec 2009
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    162

    RTAA screaming

    Hey guys and gals, I have an RTAA200 built in 92', I got sent out on the job for the 1st time a couple days ago and this is what I found. The relief valves had been replaced, the coils cleaned, some refrigerant leaks repaired, the EWT, LWT, Sat EVAP/ref. temp sensors had been replaced, and the oil filters replaced. The unit was not running due to a LWT sensor alarm. I trace this back to the board and find where the other tech just didn't have a good connecton in the plug. After that I fire up the unit to a very high pitched sound on Circuit A. I found some condenser fans running backward, fixed that. Then checked the oil level and found it was severely low. I added 4 gal of oil(system holds 8) and calibrated the differential switch. The oil level is good now and I have about 15-25psi of oil pressure diff. from my angel valve to my low side Tee on the oil line going into the comp. All this made the sound less but still there. As it starts up I am looking at 40% RLA and it loads up correctly from there, the thing is after about 30 seconds of running the high pitch noise returns until the fans stage on(15 seconds or so) and it loads up, then it goes away and runs fine. The refrigerant charge is correct to my knowledge. My question is, what else could be causing this sound? I have heard there is a check valve inside the discharge side of the compressor, could that be it? Has the damage been done due to running on a low oil level? I sent in an oil analysis and I am awaiting results. but in the mean time I turn to the pro's(you).

    Also to make matters worse I have an alarm for Compressor overload setting. I went through the dip switches and into level 5 and all settings were correct. Tech support lady told me it is a faulty board at this point. Anyone else see this before? I know that when that alarm is present it puts the settings at factory default of "00000" but how will that effect my compressor? The chillers next to it are RTAA185(2) and had the same alarms, I went through and corrected the dip switches and display settings and alarms went away so I am confident I did that part right.

    Also the Chiller with the noise does not have the EPROM upgrade FWIW. Thanks .

  2. #2
    Join Date
    Feb 2010
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    MEXICO
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    472
    tons volts RLA EXT/CT DIP/SW
    100 200/230.60 375 -05 11010/26
    460/60 163 -03 10000/16
    575.60 131 -02 10110122
    Last edited by servicetrane; 08-25-2011 at 05:04 PM.

  3. #3
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    Quote Originally Posted by servicetrane View Post
    tons volts RLA EXT/CT DIP/SW
    100 200/230.60 375 -05 11010/26
    460/60 163 -03 10000/16
    575.60 131 -02 10110122
    This.

  4. #4
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    Jun 2010
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    Tampa, FL
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    101
    Are you sure the main oil solenoid is working properly?

  5. #5
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    Mar 2004
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    ottawa canada
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    2,075
    Low oil will make them noisy . Without knowing the ability of the techs who have worked on it before and without you posting a full set of readings using the UCM and a set of real refrigerant gauges to make sure the UCM readings are true its a crap shoot . Im thinking non condensables .
    What oil did you put in it ? Where did the old oil go ?? What pressure setting and how did you calibrate the oil DP switch
    The Eprom upgrade dont matter S&%t as long as all the fans are on the coils are SPOTLESS clean especially the top 6" where the oil cooler is and all the fans run in the right direction .providing you dont have a really bad air recirc issue due to the units being to close to each other etc .
    The 64 roars to life Whoo hoo ...shes a rolling chassis .
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    Best Austin Healey In Show twice in 2013 .....All those hrs paid off .

  6. #6
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    Dec 2009
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    Quote Originally Posted by deltap10 View Post
    Are you sure the main oil solenoid is working properly?
    The solenoid has magnetism and the pressure port is after it so by the diff. pressure I have to say yes it is opening.

    [QUOTE=graham;11131532]1.Low oil will make them noisy . 2.Without knowing the ability of the techs who have worked on it before and without you posting a full set of readings using the UCM and a set of real refrigerant gauges to make sure the UCM readings are true its a crap shoot . Im thinking non condensables .
    3.What oil did you put in it ? 4.Where did the oil go?? 5.What pressure setting and how did you calibrate the oil DP switch
    The Eprom upgrade dont matter S&%t as long as all the fans are on the coils are SPOTLESS clean especially the top 6" where the oil cooler is and all the fans run in the right direction .6.providing you dont have a really bad air recirc issue due to the units being to close to each other etc .[/QUOTE]

    1. My original thought which is why the 1st thing to do was check the oil level.
    2. It is my 2nd week at this company so I do not either.
    3. 5W 30 Trane oil 015
    4. The relief valves had blown before I started and were dripping which is why they were replaced. Most likely due to dirty coils.
    5. Used nitrogen on the low pressure side, pumped it up to roughly 42psi below the guage pressure @ the angle valve and moved the thumb wheel until the switch closed.
    6. No air flow recirc issues.

    The oil pressure read at the angle valve when loaded was around 250psi and then 225psi at the low side oil port. The head pressure read at the display was 285psi with an ambient of 87*F, I know thats not as accurate as a gauge reading but its all I have at the moment. About the non condensables? Wouldn't that raise my head pressure to the point of low oil flow trips or oil temp alarms? I won't be back until I get the results of the oil analysis(1-2 weeks) so I can't get the gauge reading I would like to. Thanks so far for the suggestions.

  7. #7
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    Dec 2010
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    Down by the river
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    how many hours on the comp's?
    It's hard to stop a Trane. but I have made one helluva living keeping them going.

  8. #8
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    Quote Originally Posted by Southern Mech View Post
    how many hours on the comp's?
    a little over 20k each.

  9. #9
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    next thing that scares me is oil pressure diff. you say 15-25?. Oil press dif is the disharge - suction. Oil pressure is this. You have an oil system problem.

    You need a full set of reading's, Suction, discharge, liquid, superheat, subcool, discharge superheat, water in-out, air in-out, water flow, oil temp. How's the comp sweating? just motor, 1/2 way up rotors, to the head?. All with gauges, and compare to the CPU. are they =?.

    20K is not that many hrs on a compresor.


    next is how familiar are you with a screw compressor? they make some noise. Especially unloaded.

    You say coils are clean as a whistle, but they are 4'' thick, don't go by the surface.
    It's hard to stop a Trane. but I have made one helluva living keeping them going.

  10. #10
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    Dec 2009
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    Quote Originally Posted by Southern Mech View Post
    next thing that scares me is oil pressure diff. you say 15-25?. Oil press dif is the disharge - suction. Oil pressure is this. You have an oil system problem.

    You need a full set of reading's, Suction, discharge, liquid, superheat, subcool, discharge superheat, water in-out, air in-out, water flow, oil temp. How's the comp sweating? just motor, 1/2 way up rotors, to the head?. All with gauges, and compare to the CPU. are they =?.

    20K is not that many hrs on a compresor.


    next is how familiar are you with a screw compressor? they make some noise. Especially unloaded.

    You say coils are clean as a whistle, but they are 4'' thick, don't go by the surface.
    See bottom paragraph on post #6 for oil pressure. I need to get gauge readings but judging by the display and no other alarms I am assuming(I know) that my coils are clean or at least not the issue at hand. comp is sweating half way up. I am familiar enough with them to know the noise it makes isn't normal. Thank you for the suggestions thus far.

  11. #11
    Join Date
    Apr 2011
    Location
    Florida
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    2
    Hello, I have been reading your thread and the similarity to my present call prompted me to ask what the outcome was? I have an RTAA 200 with different circumstances initiating the call. The customer called me on a holiday and did not want immediate service just how to stop the noisy circuit until I could come out on regular time. I get there only to find the system with no gas and no apparent oil. Oil DP switch was bad along with saturated condenser temp sensor. No significant amount of oil on the ground. Have not found the oil yet. Thinking it must have gone to the barrel. It is not in the oil cooler or the separator. I am not going to put the circuit back in operation until I have found the oil and removed it. I also intend on checking slide valve operation before recharging etc. . Looks like suction bypass block kit was installed on the unit but piston was not replaced at that time. So far, Oil DP,saturated condenser temp sensor, discharge relief, oil filter and filter drier cores have been changed. System has been leak tested, evacuated and a holding pressure applied. Would like to hear from you on the outcome of your screamer. Sincerely, Don Juliano

  12. #12
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    Quote Originally Posted by JULIANOD View Post
    ...Have not found the oil yet. Thinking it must have gone to the barrel. It is not in the oil cooler or the separator. I am not going to put the circuit back in operation until I have found the oil and removed it. I also intend on checking slide valve operation before recharging etc....
    i would be interested in knowing how you plan on getting the oil out of the barrel before putting it back into operation...or how you will check the slide valve operation.
    When the rich wage war, it's the poor who die - Linken Park

  13. #13
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    Dec 2009
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    Quote Originally Posted by JULIANOD View Post
    Hello, I have been reading your thread and the similarity to my present call prompted me to ask what the outcome was? I have an RTAA 200 with different circumstances initiating the call. The customer called me on a holiday and did not want immediate service just how to stop the noisy circuit until I could come out on regular time. I get there only to find the system with no gas and no apparent oil. Oil DP switch was bad along with saturated condenser temp sensor. No significant amount of oil on the ground. Have not found the oil yet. Thinking it must have gone to the barrel. It is not in the oil cooler or the separator. I am not going to put the circuit back in operation until I have found the oil and removed it. I also intend on checking slide valve operation before recharging etc. . Looks like suction bypass block kit was installed on the unit but piston was not replaced at that time. So far, Oil DP,saturated condenser temp sensor, discharge relief, oil filter and filter drier cores have been changed. System has been leak tested, evacuated and a holding pressure applied. Would like to hear from you on the outcome of your screamer. Sincerely, Don Juliano
    I never got to go back on it. I "heard" the slide valve got replaced by another contractor. Good luck with your machine and I guess make sure you check that slide valve.

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