RTAA screaming

[929rc51]

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 .

[servicetrane]

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

[929rc51]

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.

[deltap10]

Are you sure the main oil solenoid is working properly?

[Healey Nut]

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 .

[929rc51]

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.

[Southern Mech]

how many hours on the comp's?

[929rc51]

how many hours on the comp's?

a little over 20k each.

[Southern Mech]

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.

[929rc51]

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.

[JULIANOD]

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

[jayguy]

...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.

[929rc51]

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.

[JULIANOD]

I should have said that I intend to check the piston while the system is down. The service bulletins available describe it better. I am concerned about the possibility that the piston might be sticking. This is not the first time the system has done this. I could not confirm at what time of day or what the sequence was which started this. Its been almost 3 yrs since the last occasion. I am wondering if this could have been " morning syndrome". No codes where available when I arrived. Owner knew how to reset and clear history. It was a holiday and I'm not sure which compressor was lead at that time or how long it had been off.
The oil I have removed is not good. Testing indicates moisture but not at really high levels. Color was darker than I'm used to. Since I'm not sure how much was lost and have moisture and an odd color. My decision to change the oil is mostly because I am already pretty much there. Yes, I know flushing a barrel is costly and not 100% successful. At this point, I have not verified that a large quantity of oil is in the barrel. Could have been low to start with. I am only called when they cannot make things run! Nice to be needed. LOL

[alcomech]

I should have said that I intend to check the piston while the system is down. The service bulletins available describe it better. I am concerned about the possibility that the piston might be sticking. This is not the first time the system has done this. I could not confirm at what time of day or what the sequence was which started this. Its been almost 3 yrs since the last occasion. I am wondering if this could have been " morning syndrome". No codes where available when I arrived. Owner knew how to reset and clear history. It was a holiday and I'm not sure which compressor was lead at that time or how long it had been off.
The oil I have removed is not good. Testing indicates moisture but not at really high levels. Color was darker than I'm used to. Since I'm not sure how much was lost and have moisture and an odd color. My decision to change the oil is mostly because I am already pretty much there. Yes, I know flushing a barrel is costly and not 100% successful. At this point, I have not verified that a large quantity of oil is in the barrel. Could have been low to start with. I am only called when they cannot make things run! Nice to be needed. LOL

Well have you got it running yet?

Troubleshooting is not part of the repair.............understand the symptoms and you will find a solution.

[929rc51]

Well first time back on the job site since last year. I wasn't working in this particular chiller but I walked over to check on it and this is what I find...




Can anyone explain this? In case you can't see it in the pictures the steal braided line comes off the plate in front of the load/unload and goes to a port on the bottom of the comp.

[valdelocc]

Well first time back on the job site since last year. I wasn't working in this particular chiller but I walked over to check on it and this is what I find...




Can anyone explain this? In case you can't see it in the pictures the steal braided line comes off the plate in front of the load/unload and goes to a port on the bottom of the comp.

looks like the lip seal leaked and it got mended.

[alcomech]

Lip Seal Failure.
What is the serial number for the compressor?

[Healey Nut]

That is a lip seal re-route kit , it wont hurt the compressor even if the lip seal was NOT leaking . Its a common fix on the larger RTAA compressor .When the lip seal leaks the compressor usually loads on its own without signals from the UCM the re-route kit diverts the leaking pressure back to the suction side of the compressor . As long as the re-route kit can handle the small amout of leak it will be fine if the leak exceeds the re-route kit capabilitys then you have to replace the compressor.

[929rc51]

I don't have the serial of the comp. I'll get it tomorrow if I remember.

Thanks for your help guys. I now have another issue on another rtaa but I'll start a new thread about it if I have to. Trying to use that search function first