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  1. #40
    Join Date
    May 2002
    Location
    evansville indiana
    Posts
    943
    Quote Originally Posted by R123 View Post

    for

    No.
    The oil level switch verifies there is OIL in the sump. The oil pressure at the compressor is determined by the differential pressure between the discharge pressure transducer, oil pressure transducer, & suction pressure transducer. If there is no oil in the sump, the oil pressure transducer will be reading REFRIGERANT pressure, not OIL pressure. It doesn't know the differance.
    for differential oil pressure the controls look at the difference between the econmizer transducer and the oil pressure transducer .....the economizer transducer is the highest low pressure in the compressor and is higher than the suction pressure ...discharge pressure drives the oil but does not factor in the oil diff calculation .... Filter diff calc yes...oil press diff ...noooooo...

    side note.. Their is about a billion software revisions .... I believe discharge pressure is watched to make sure it rises Fast enough and high enough to push the oil ...later on they started allowing the oil pumps to cycle back on if need be to eliminate nuciance shutdowns ...


    the manual used to and may still have listed the Einstein equation the controls use to prove proper oil pressure . it can be very confusing.


    If I'm wrong I'll quit the trade and go be a strip club DJ

    If i make no sense I'll sit out in the sun again tomorrow and cook my brain some more then come back for seconds....
    mikeacman

  2. #41
    Join Date
    May 2002
    Location
    evansville indiana
    Posts
    943
    Tommyknocker.....

    I'm telling troy what you did.
    mikeacman

  3. #42
    Join Date
    Jul 2007
    Location
    The Hot South
    Posts
    1,367
    Quote Originally Posted by Tommy knocker View Post
    So R123 what danger exactly are you referring too? Let's try this. In your expert opinion will the oil pump produce enough vapor refrigerant pressure to fool the oil pressure transducer if no oil is in the seperator?
    No, the oil pump will not produce any vapor refrigerant pressure to fool the oil pressure transducer if no oil is in the seperator, and in that case the compressor won't start. But, once the compressor starts, the pre lube pump shuts down and at this point oil is flowing due to differential refrigerant pressure pushing the oil in the seperator, through the filters and oil solonoid valve, and on into the compressor. If the oil level runs out at this point (after the pre lube pump shuts down), then yes, the vapor refrigerant pressure could fool the oil pressure transducer. Thats why the oil level switch is in there.

  4. #43
    Join Date
    Jul 2007
    Location
    The Hot South
    Posts
    1,367
    Quote Originally Posted by mikeacman View Post
    for differential oil pressure the controls look at the difference between the econmizer transducer and the oil pressure transducer .....the economizer transducer is the highest low pressure in the compressor and is higher than the suction pressure ...discharge pressure drives the oil but does not factor in the oil diff calculation .... Filter diff calc yes...oil press diff ...noooooo...

    side note.. Their is about a billion software revisions .... I believe discharge pressure is watched to make sure it rises Fast enough and high enough to push the oil ...later on they started allowing the oil pumps to cycle back on if need be to eliminate nuciance shutdowns ...


    the manual used to and may still have listed the Einstein equation the controls use to prove proper oil pressure . it can be very confusing.


    If I'm wrong I'll quit the trade and go be a strip club DJ

    If i make no sense I'll sit out in the sun again tomorrow and cook my brain some more then come back for seconds....
    I think your right.

  5. #44
    Join Date
    Jun 2012
    Posts
    529
    Quote Originally Posted by mikeacman View Post
    If I'm wrong I'll quit the trade and go be a strip club DJ
    After the evapco I fought today that sounds like a better career choice hahaha

  6. #45
    Join Date
    Feb 2012
    Location
    utah
    Posts
    106
    I have been reading this for days and have been trying real hard to stay away but alas I cant. Carrier procedure is to add oil (1/2 gallon)to get machine to start, operate in a high load state, check ref. charge and then remove the oil.
    Now have I ever done this? let me just say that every one of my hx and gx machines have the oil level sensor wires striped at some point just wide enough for a jumper. I have never had to leave it on for more then 3 or 4 min. if you do its probably the charge or some other problem.
    in this case the tubes are probably pluged and the unit is oversized which causes it to stay in a low load condition for extended times. clean the tubes, increase the deadband, start the smaller comp first, and properly check the charge. the oil is there, run the machine properly and it will be fine.

  7. #46
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    OK so we agree that the comp is protected from no oil on start if level switch is jumped out. Now once running would vapor refrigerant absent of oil produce the pressure differential the control is looking for?

  8. #47
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,725
    Quote Originally Posted by Tommy knocker View Post
    So R123 what danger exactly are you referring too? Let's try this. In your expert opinion will the oil pump produce enough vapor refrigerant pressure to fool the oil pressure transducer if no oil is in the seperator?
    I know this question is for R123 but under the right circumstances it is possible to have the control to start a compressor with the oil level switch open and the prelube just enough to make pressure.
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  9. #48
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    I suppose. Sorta like a piece of straw can penetrate concrete "under the right circumstances"

  10. #49
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,725
    Quote Originally Posted by Tommy knocker View Post
    I suppose. Sorta like a piece of straw can penetrate concrete "under the right circumstances"

    Sure why not , open an oil level switch next time and start a compressor and see if it starts.
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  11. #50
    Join Date
    Jun 2012
    Posts
    529
    Quote Originally Posted by Dallas Duster View Post
    Sure why not , open an oil level switch next time and start a compressor and see if it starts.
    "I have been reading this for days and have been trying real hard to stay away but alas I cant. Carrier procedure is to add oil (1/2 gallon)to get machine to start, operate in a high load state, check ref. charge and then remove the oil.
    Now have I ever done this? let me just say that every one of my hx and gx machines have the oil level sensor wires striped at some point just wide enough for a jumper. I have never had to leave it on for more then 3 or 4 min. if you do its probably the charge or some other problem.
    in this case the tubes are probably pluged and the unit is oversized which causes it to stay in a low load condition for extended times. clean the tubes, increase the deadband, start the smaller comp first, and properly check the charge. the oil is there, run the machine properly and it will be fine."

    ^works for him, me, and others with no catastrophe. Nobody must do it this way it is just an option. These machines are notorious for this and it is just another option. Many people do this if they are familiar with the particular machine and it's history. Say for instance a compressor was locked out for some time while another compressor was running the oil may migrate and once brought back online it would have a fit. This is just a quick tip of getting it back up and gunning.

  12. #51
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,725
    Quote Originally Posted by Freightshaker View Post
    "I have been reading this for days and have been trying real hard to stay away but alas I cant. Carrier procedure is to add oil (1/2 gallon)to get machine to start, operate in a high load state, check ref. charge and then remove the oil.
    Now have I ever done this? let me just say that every one of my hx and gx machines have the oil level sensor wires striped at some point just wide enough for a jumper. I have never had to leave it on for more then 3 or 4 min. if you do its probably the charge or some other problem.
    in this case the tubes are probably pluged and the unit is oversized which causes it to stay in a low load condition for extended times. clean the tubes, increase the deadband, start the smaller comp first, and properly check the charge. the oil is there, run the machine properly and it will be fine."

    ^works for him, me, and others with no catastrophe. Nobody must do it this way it is just an option. These machines are notorious for this and it is just another option. Many people do this if they are familiar with the particular machine and it's history. Say for instance a compressor was locked out for some time while another compressor was running the oil may migrate and once brought back online it would have a fit. This is just a quick tip of getting it back up and gunning.

    So it's safe to say that you are doing performing a repair incorrectly against factory recommendation and risk and accept the consequences?
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  13. #52
    Join Date
    Jun 2012
    Posts
    529
    Quote Originally Posted by Dallas Duster View Post
    So it's safe to say that you are doing performing a repair incorrectly against factory recommendation and risk and accept the consequences?
    Guilty as charged I guess. I read an Evapco manual yesterday and it mentioned waxing the stainless steel components in their cooling towers. I can't really say I do that either or ever really heard of anyone doing it.

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