RTAA125 1mo time

[mkitrtfst]

Called out on alarm for compressor replaced couple days ago. diagnostics tells shut down on "oil system fault". Checked pressure drop across oil filter, right on the chart for NORMAL line. watched equipment operation, oil temperture running average 10 to 6 degrees below sat. cond. temperture. Shuts down on 1/2 hour run time,as it should. Application is process water, load is varied as city water fills storage tank,oil level was checked on seperator, 10" from bottom after 10 min.shut down. I have oil filter to change for tomorrow but i do not think this is it. any help is appreciated.

[chiller32]

the oil diff switch may be going badf i have replace a few

[mkitrtfst]

this unit uses diff of sat.cond. temp. to oil temp at the compresor in processor for safty shut down.

[cold-n-mode]

If you compare the sat cond temp sensor against a thermometer reading i bet you find the sensor reads higher/lower than actual this will cause the oil system fault,if not this one check the oil sensor on the front of the compressor one of the two are bad!

[mkitrtfst]

Put my fluke clamp on temp.sensor on oil inlet at compressor.Sensors are showing same. Checked condensor pressure to sat. temp. check ok.

[cold-n-mode]

Originally posted by mkitrtfst
Put my fluke clamp on temp.sensor on oil inlet at compressor.Sensors are showing same. Checked condensor pressure to sat. temp. check ok. try a strap on thermometer,one of the sensors is bad,i had this same promlem two weeks ago had to replace the condenser sensor ,converting the pressure will not work.

[hsc tech 1]

Best advice I can give On RTAA, don't trust the micro on pressure or temp reading ,when you have a trip. Check the temp and pressure yourself. Had the same broblem. Oil diff.
control was all that was wrong. Hope this help

[mkitrtfst]

Thanks,will do just that in morning,confidence gets low when it everything looks right.

[hsc tech 1]

mkit, you will do fine, we all have been there before, right guys ???

[cold-n-mode]

Originally posted by hsc tech 1
mkit, you will do fine, we all have been there before, right guys ??? keep your chin up it happens to all of us

[mkitrtfst]

I tell ya. This has been frustrating, new cuttler/hammer contactor on replacement compressor is faulty,spring to hold coil away from contactor is installed sideways, compressor shuts down on single phase.you think you are doing right staying with oem but that stuff can eat you up!

[R12rules]

Originally posted by mkitrtfst
I tell ya. This has been frustrating, new cuttler/hammer contactor on replacement compressor is faulty,spring to hold coil away from contactor is installed sideways, compressor shuts down on single phase.you think you are doing right staying with oem but that stuff can eat you up!

That's what happens when they begin letting kids assemble parts overseas!

[cold-n-mode]

Originally posted by mkitrtfst
Thanks,will do just that in morning,confidence gets low when it everything looks right. hey did you find the bad sensor,or fix the chiller?

[twcpipes]

Just some questions in passing:

1. If the temp differential is 10-6 degrees, at what point does the safety open?
2. Does the safety see a closer temp or a farther apart temp?
Thank you.
tom

[mkitrtfst]

rained all day,sent me on another location,to answer questions on last post. This unit uses the UCP sensor inputs of sat. cond temp.and oil temp. OILtemp. cannot fall any lower than 4 degrees of sat. temp for 1/2 hr. If so unit shuts down on manuel reset. pressure switch is used for a high limit only.

[mkitrtfst]

Trying to get there this morning.

[twcpipes]

That is an interesting way to monitor oil temp. Why did you have to replace the compressor? Also, how old is this unit as I am sure "it has always worked" with this oil control set-up.
Thanks again.

[flemsteele]

If you have Trane Eagle check the service bulletins there many things that cause that trip.

1) Check your condenser fans ... are they all running?

2) Check your slide valve position by reading compressor amps at start up . Should be about 30%-35% of RLA. If you read higher your slide valve may be stuck .

[mkitrtfst]

System stayed on line all day.Confirmed sat. cnd temp.accuracy, oil sensor accuracy, start up normal,did not check fans. INTERMITENT SAT. COND. sensor probably is the culprit. If to many fans are on, oil is overcooled,"oil system fault" is activated. First compressor failed on bearing failure, system is over 5 year old.Thanks again,when i find the culprit, will inform.

[mathias]

I am an ex Trane guy and had a call on RTAA last week that had been serviced by Trane which was a wreck with same problem. Had bad suction sensor - replaced ran ok for 15 minutes started again doing same!!! Oil differential switch in pecker head of compressor - adjusted from 40 to 60 - workeds fine now!!! don't waist the oil filter - too expensive!!!

[trimble]

Originally posted by mathias
I am an ex Trane guy and had a call on RTAA last week that had been serviced by Trane which was a wreck with same problem. Had bad suction sensor - replaced ran ok for 15 minutes started again doing same!!! Oil differential switch in pecker head of compressor - adjusted from 40 to 60 - workeds fine now!!! don't waist the oil filter - too expensive!!!

The RTAA 70 - 125 uses temperature differential between sat cond temp and oil temp. RTAA 130 and above uses an oil pressure switch.

He doesn't have an oil pres switch.

Make sure all fans are running. You may have a cloged filter... especially if you had a bearing failure. You may have had trash in the oil and cloged up the filter in the new compressor.

[no8no3]

These units have several confidential bullitens on them concerning oil DP. I had one that i worked on for a week, tried everything with no luck....Straight wired all cond. fan motors, and kept it going for a month. Trane had re-programed the motors with a software glitch, as if this unit wasn't challenged enough. This work was done a year or two ago, along with 6000.00 dollars worth of other things that never worked.

I dont blame trane for this problem, just their engineer's...You know, the ones that say it will work, and then have to author all those bullitens. In a nutshell, this unit has not performed as well as expected and the damage control that Trane has effected is too late. I've actually had Trane techs tell me to jump it out. NOT GONNA HAPPEN. It so happens that this customer has 3 units, and luckily only one circuit still has an occasional problem.

I havn't counted the list of possible cures for this problem as touted by trane, but i'd guess the number at about 30. I'm not suggesting a recall, but it would be nice to get these problems resolved without us both looking like fools.

[roadking]

dirty condenser can cause that but most likey it a bad oil press. diff. switch. have them go bad all the time.

[chillerguru]

I had the same problem. I had a faulty EXV overfeeding liquid refrigerant that eventually cooled the oil where the sensor is on the compressor.

[hsc tech 1]

txtraneman, is right on, check the condenser fans .
If the fans do not come on ,time versus saturate temp in the micro, it may be going into panic mode, causing all condensor fans to run. Diagnostics trip.
Condensor saturate sensor control the fans,I use a resister box or decade box to dial in the temp to troubleshoot the problem. Also manual push all cond. fan contacts in to make sure all fans are working and correct rotations.
Something as simple as a condensor fan motor or motors can be the fix.

[mkitrtfst]

checked on equipment yesterday, no history of any shut downs, checked fans,confirmed sensor accuacy on sat. cond. Overfeeding exv,interesting thought,system load changes quickly,city water is used for processing,water valve feeds into ent water pipe 40 feet b-4 chiller.o degree superheat all to often is occuring.first compressor failure was bearings,this could be it,go back and restrict water fill to offer less temp change on ent. water. thanks again for everyone input!

[hsc tech 1]

mkitrtfst,0 degree superheat? I was thinking.4 to6, have to get the old book out.Superheat suould be set in the micro.After the parimeters are set, the micro takes over.TEVs are control by combination of suction sensors temp outlet of evap, and suction of compressor. Only trying to give you info if this helps.

[hvacker]

Remember when it was said if you don't find why a compressor failled the next one will probably fail too. The first you said had bearing failure. This is almost always due to refrigerant washing the oil from the bearings. If the problem wasn't fixed with the first compressor you might get revisited.

[deanm]

Trane has had problems with their O.D.P. switches since they have been making these rtaa's. I was Trane Factory Service Rep for many years and the first thing we did when this problem came up was to replace switch with one that you feel confident in! Switch opens at 49#'s. Always check new switch b4 installing to make sure all is OK.

[trimble]

Originally posted by deanm
Trane has had problems with their O.D.P. switches since they have been making these rtaa's. I was Trane Factory Service Rep for many years and the first thing we did when this problem came up was to replace switch with one that you feel confident in! Switch opens at 49#'s. Always check new switch b4 installing to make sure all is OK.

As mentioned many times above, the RTAA125 doesn't use an oil pressure differential switch for oil protection. It looks at the difference between saturated condensing temp and oil temp for oil protection. When the Entering Oil Temp on either compressor of the given circuit reads a temperature 4 degrees below the given ckts' saturated condenser temp for more than 30 minutes, it trips that circuit. The RTAA 130 and above uses an O.D.P. which you must replace with an auto reset switch.