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Thread: Trane Chiller

  1. #1
    Join Date
    Dec 2003
    Posts
    148
    We’ve got a Trane Chiller, Model #RTAA1854XT01A0C0F, I believe it’s 185 tons, air cooled condenser, with two separate circuits, circuit #1 is 100 tons, and circuit #2 is 85 tons. The problem we are having is circuit #1 will run for appx 30 sec. and cut out, the code we are getting is 194(Low Evap Rfgt Temp-Crtct 1). We are suspecting that the electronic expansion valve is not operating correctly because when circuit #2 starts the valve opens right before the compressor starts, however, circuit #1 does not; the compressor starts and the low side immediately pulls down to 10 inches of vacuum and cuts out. Head pressure remained constant at 150psi. Does anyone have any ideas as to what we should test, what kind of voltage should we read at the EXV? Would a bad sensor cause the EXV to not open? Hopefully Trane will come out and look at this Monday or Tuesday, but in the mean time, circuit #2 just can’t keep up with the load. Any help or ideas would be appreciated.
    Still learning....

  2. #2
    this at the zoo?

  3. #3
    Join Date
    Aug 2003
    Posts
    242
    There are several things that can cause this problem. When you say it is pumping down to 10” of vacuum, are you going by your gauges, or the UCM? You can have a bad saturated suction temp or comp suction temp sensor. You can also have a bad EXV. You need to do an EXV test. This procedure, as well as many other tests, is in Trane Service Bulletin RTAA-SB-5 “Control Operation, Setup and Troubleshooting for RTAA Series R Air-Cooled Chiller Control Panel. UCM.”

    I have this service bulletin in PDF format and I can Email it to you.

  4. #4
    Join Date
    Dec 2003
    Posts
    148
    Yes, this is at the zoo, the 10" of vacuum was taken off the guages, not the UCM. txtraneman, if you could email me that service bulletin I would really appreciate it. agrossm@charter.net Thanks!
    Still learning....

  5. #5
    Join Date
    Dec 2003
    Posts
    148
    THANKS!! for the service bulletin, I'm going to look it over tonight, hopefully we'll have some answers tomorrow. I appreciate your help, Adam.
    Still learning....

  6. #6
    Join Date
    Jan 2004
    Posts
    1,174
    BTW, screws do not like being pulled into a vacuum, you might not want to keep doing it.

  7. #7
    Join Date
    Aug 2004
    Location
    U.S. Air Force
    Posts
    6
    I am having a problem with a Trane chiller with screw compressors. We replaced the EXV and sensors for circuit 2, but as we were doing this circuit 1 went down on us. The first code said it was off on low superheat and then we reset it and it went off on low oil pressure. We checked the oil level and it looks good. The main thing we have noticed and its really aggrevating us is that none of the condenser fans will cycle on. The compressor will run for about 2 minutes until it reaches about 50psi suction and about 325psi head. We've checked all the fans and they check out good. Now we have narrowed the problem down to a bad circuit board. If anyone has had this problem and can give some advice I would really appreciate it. So would the 3000 soldiers who are living in the barracks, which are being supplied cooling from this chiller.

  8. #8
    Join Date
    Dec 2002
    Posts
    9,871

    SENSORS

    Have been the scourge of RTAA's. Also the umbilical to the EXV may have some broken wires due to vibration.

  9. #9
    Join Date
    Oct 2001
    Posts
    6,945
    on fans staging....verify your outdoor air temp on the panel is reading within the actual days temp.it is located under the electrical panel repin it and take an OHM reading on it while out.do you have the manual on this machine

  10. #10
    Join Date
    Aug 2004
    Location
    U.S. Air Force
    Posts
    6
    So you think that the outside air sensor may be loose or something? I'll make sure they are tight. We do have a manual, but I don't have it with me at the moment. Thanks for your reply. Also, thanks Rob10 I'll check it out.

  11. #11
    Join Date
    Oct 2001
    Posts
    6,945
    check it at the pins and it wouldn't hurt to re-pin all the boots on all the modules with the disconnect down.do you have a Human Interface "tan" panel UCP-2 on the access door or the UCP-1 blue LED read out style inside the door?that oil pressure trip is the differential on the filter saftey switch that takes the difference on the oil into the filter and the oil going to the compressor...located up in the condenser above the compressor near the filter.

  12. #12
    Join Date
    Aug 2004
    Location
    U.S. Air Force
    Posts
    6
    ok, I'll re-pin all the boots. That's the first thing I'll do in the morning. I'm not sure if I know what you mean by the UCP-1 or UCP-2. If you are talking about the display board, I think I have the UCP-2. I don't have much experience with this type chiller so apologize if it seems like i'm not on the same page. But the numbers and letters on the display are blue. Is that what you mean? The mechanics in the past had bypassed the normal oil line from the top by crimping the line and placing a refrigerant hose from the service valve by the filter to the pressure switch. I'm not sure why they decided to do that. Thanks

  13. #13
    Join Date
    Oct 2001
    Posts
    6,945
    that's a UCP-1 you have and all the boards have the pins and all sensors you have on the 1st circuit are duplicated on the 2nd.the O/A is for the entire unit telling the main module how to stage and run with the ambient reading.

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