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Thread: RTAA1404

  1. #1
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    RTAA1404

    working on a rtaa 140 ton
    1991 model, twin screw.

    the question that i have is about the common, 198, 199, diag.,
    now i know about the hi discharge temp can cause low oil flow diag, due to the velocity,

    also i know about dirty coils, filter, fan, and fans running backwards, and also non condensiables,

    i did a pd across the oil filter and is only about 2-10 lb pd across oil filter, cleaned the coils on maint, all fan working and not running backwards.

    i told customer these r the issues that can cause this and what i have checked,

    i suggested the oil filter, liquid line filter be changed due to know knowing when last time this has been done., i was going to calibrate the oil pressure switch, and he told me just to replace the switch, oil and refrig filters,
    ...
    now it there anything else that can be done, im thinking not,
    has anyone had problems with the mechanical oil switch going bad,?
    any other suggestions?
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  2. #2
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    I've replaced several of those oil pressure switches on the older air and water cooled R series Tranes.

    I would check voltage across the switch contacts while reading DP with my gauges. I think the switch is factory set around 50#
    Saving the world...one service call at a time.

  3. #3
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    check the oil pressure differential switch 'X' number. if it ends in '-03' or '-3' then change it as there was a problem with them staying in calibration...no service bulletin or anything was ever issued.

    the oil pressure differential switch does NOT monitor the pressure drop across the oil filter...it measures across the oil filter manual isolation valve, oil filter, oil line and master solenoid valve...this is what you need to measure across. any 'non-factory' add-ons will change the pressure drop.

    i am not familiar with the 'high discharge temperature' causing an oil flow diagnostic.
    "Mother" is the name for God on the lips and hearts of children....The Crow

  4. #4
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    thanks for the replies
    no signature blast'em man blast'em
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  5. #5
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    make sure the compressors are unloading properly. also there is a service bulletin for a fan staging upgrade for chillers manufactured before 98. another thing i find is that just when i think the coils are clean i clean them again.
    i think the service bulletin is rtaa sb 21

  6. #6
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    thanks .,

    i am running across another issue,,
    cir b diag of wind temp, i told building owner that the sensor is bad, it trips as soon as i reset all diag the wind temp diag pops up right awat., i was looking at the schamitic and from what i am looking at , it seems that the wind temp sensors are in series., has anyone had this issue, this is a 1991 machine, they r going to replace this machine in the future, however, not at this time., also i told the customer that we can bypass the wind temp sensors, however , his screw compressor is at risk with no safety, he want this fixed due to this diag being a CMR..
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  7. #7
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    Quote Originally Posted by mlkwal1 View Post
    thanks .,

    i am running across another issue,,
    cir b diag of wind temp, i told building owner that the sensor is bad, it trips as soon as i reset all diag the wind temp diag pops up right awat., i was looking at the schamitic and from what i am looking at , it seems that the wind temp sensors are in series., has anyone had this issue, this is a 1991 machine, they r going to replace this machine in the future, however, not at this time., also i told the customer that we can bypass the wind temp sensors, however , his screw compressor is at risk with no safety, he want this fixed due to this diag being a CMR..
    you have a lot of issues going on here...i would recommend slowing down to make sure that you are not bypassing a WORKING safety versus jumping it out only to find that the unit had something else going on.
    "Mother" is the name for God on the lips and hearts of children....The Crow

  8. #8
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    i can understand where u r coming from,and thanks for the concern, if the compressor has a wind temp error, then either 1 of the 3 wind temp sensors failed or if the compressor continues to start and is tripping on overload, due to repete starts right? however, when i reset the diag and clear all, right off the rip the wind temp sensor alarms. also i was looking at the starts for cir 1 and cir 2, cir 1 has around 5k starts whereas cir 2 has 2200 or so., lead lag should be enabled, , this is telling me something
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  9. #9
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    Quote Originally Posted by mlkwal1 View Post
    i can understand where u r coming from,and thanks for the concern, if the compressor has a wind temp error, then either 1 of the 3 wind temp sensors failed or if the compressor continues to start and is tripping on overload, due to repete starts right? however, when i reset the diag and clear all, right off the rip the wind temp sensor alarms. also i was looking at the starts for cir 1 and cir 2, cir 1 has around 5k starts whereas cir 2 has 2200 or so., lead lag should be enabled, , this is telling me something
    i have several compressors with over 30,000 starts in about as many hours. as for the diagnostic, have you opened up the terminal box cover? ohmed the winding switches? (they are switches, not sensors. they are only open or closed) ohmed out the wiring? it could be something simple like that.

    you did not mention anything about the unit tripping on overload. what is going on there?

    lead/lag is usually a good thing to have enabled.
    "Mother" is the name for God on the lips and hearts of children....The Crow

  10. #10
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    when i say overload, i was referring to wind temp switches, thanks jay , and yes i did open the electrical box., i will upload a pic little later.,
    no signature blast'em man blast'em
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  11. #11
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    Will someone remind me of what I said about yet ANOTHER post about oil flow codes on RTAA's ???????? AAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH HHHHHHHHHHHHHHHHHHHHH
    The 64 roars to life Whoo hoo ...shes a rolling chassis .
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  12. #12
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    Quote Originally Posted by graham View Post
    Will someone remind me of what I said about yet ANOTHER post about oil flow codes on RTAA's ???????? AAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH HHHHHHHHHHHHHHHHHHHHH
    HAHAHAHAHAHAHAHAHAHA!!!!!!!!
    "Mother" is the name for God on the lips and hearts of children....The Crow

  13. #13
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    Quote Originally Posted by jayguy View Post
    i have several compressors with over 30,000 starts in about as many hours. as for the diagnostic, have you opened up the terminal box cover? ohmed the winding switches? (they are switches, not sensors. they are only open or closed) ohmed out the wiring? it could be something simple like that.

    you did not mention anything about the unit tripping on overload. what is going on there?

    lead/lag is usually a good thing to have enabled.


    i have opened the terminal box., and did ohm out switches, they r closed., i will ohm wiring ., thanks j
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