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  1. #1
    Join Date
    Jan 2004
    Posts
    164

    Confused Trane guys I have a question

    Ok here it goes I have a Trane mod. SEHFC754N167A8AD9C01A0W00G0K000RT008000 ser. C02c01857
    Let me first explain I am not a apprentice and I have a Trane unit as mentioned above that is having issues on above 95 degree days. We which is one of my top teck and I have looked at this unit and found that the condenser is under sized at the design load conditions. I will give the details we are seeing. first I live in Denver and we don't have near the air you guys do at sea leavel so here are the readings. Trying to maintain a discharge air of 55 degrees and the oat is 95 with a 30% humidity level on the day we are seeing this. Pressures are at 70 suction with a 20 degree superheat as we removed freon to confirm what we were seeing and the discharge pressure was at 410 plus and rising and it tripps at 420psi. We removed enough Freon R-22 to get as low as 4 degrees subcooling and it still tripps if all three compressors are runing. I cleaned the condenser coil for circuit #2 just to see what would happen and the unit would stablelize at 410 psi but we did notice the fan blades have been changed with 5 blade fans and they are at rated amps and this was done by trane after the oringinal install.
    so here we are trying to figure this out. We disconnected one compresor on both circuits and the unit will cool the space and stay running. So I am wondering if the condenser is under sized as we removed enough freon to where the superheat will continue to rise. Any thoughts
    If you find it bad 3 different ways- ~its bad~

  2. #2
    Join Date
    Feb 2009
    Location
    Fox Lake IL
    Posts
    438
    Did you pull the condensor coils apart to clean them.

  3. #3
    Join Date
    Dec 2010
    Location
    Down by the river
    Posts
    1,620
    Quote Originally Posted by GREGHVACGUY View Post
    Did you pull the condensor coils apart to clean them.
    I pack is not a split coil
    It's hard to stop a Trane. but I have made one helluva living keeping them going.

  4. #4
    Join Date
    Dec 2010
    Location
    Down by the river
    Posts
    1,620
    have you pulled charge an weighed?
    It's hard to stop a Trane. but I have made one helluva living keeping them going.

  5. #5
    Join Date
    Feb 2006
    Location
    Phoenix,AZ
    Posts
    2,847
    I know what's wrong it! The model numbers too long! Throw it in the garbage!

  6. #6
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361
    Quote Originally Posted by teckster View Post
    Ok here it goes I have a Trane mod. SEHFC754N167A8AD9C01A0W00G0K000RT008000 ser. C02c01857 Packaged unit, commercial with 3 (or 4??) compressors, 2 separate circuits. Let me first explain I am not a apprentice and I have a Trane unit as mentioned above that is having issues on above 95 degree days. We which is one of my top teck and I have looked at this unit and found that the condenser is under sized at the design load conditions. I will give the details we are seeing. first I live in Denver and we don't have near the air you guys do at sea leavel so here are the readings. Trying to maintain a discharge air of 55 degrees and the oat is 95 with a 30% humidity level on the day we are seeing this. Pressures are at 70 suction with a 20 degree superheat as we removed freon to confirm what we were seeing and the discharge pressure was at 410 plus and rising and it tripps at 420psi. We removed enough Freon R-22 to get as low as 4 degrees subcooling and it still tripps if all three compressors are runing. I cleaned the condenser coil for circuit #2 just to see what would happen and the unit would stablelize at 410 psi but we did notice the fan blades have been changed with 5 blade fans and they are at rated amps and this was done by trane after the oringinal install. Are all of the blades' rotation correct? so here we are trying to figure this out. We disconnected one compresor on both circuits and the unit will cool the space and stay running. So I am wondering if the condenser is under sized No way. as we removed enough freon to where the superheat will continue to rise. Any thoughts
    Previous techs may have left air or nitrogen in the systems. Even R410A is possible. In any event the purity of the refrigerant must be checked against a PT chart. Recover the refrigerant, test the purity, recharge with pure R22 by weight and see what happens. Restricted driers ahead of the SC temperature reading point could be hiding an overcharge.There is no reason why the discharge pressure should exceed 340 psig on a 100F ambient. Recirculation of condenser discharge air or wind may contribute to your problem but I doubt that this would be a major factor.
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

  7. #7
    Join Date
    Sep 2008
    Location
    Woodsville, NH
    Posts
    1
    I agree with the above statement. must pull apart coil. with multi circiuts there is more then one coil on top of each other and from the outside coil may look clean but when pulled apart there will be a thick layer of dust. If still a problem and is believed to be first statement, then remove all refrigerant, purge, evacuate and recharge with factory amount of refrigerant. Also never hurts to call Trane tech support they are very helpfull.

  8. #8
    Join Date
    May 2000
    Location
    Stafford, Va. USA
    Posts
    213
    Hi Teckster,
    The IntelliPak unit does NOT have a split coil like the Voyager II units. The IntelliPak has a single coil as Southern Mech stated.
    Do the procedures that Lynn Comstock has recommended. Pay close attention to the liquid line drier, if it is stopped up and the unit was running low suction, someone may have thought the unit is low on refrigerant, and added some refrigerant. Now the unit is overcharged and running high head pressure.
    The condenser is not undersized. Your unit was built in March of 2002, the temperatures have certainly been at 95 degrees or higher since then. That sort of problem would have been found before now.
    Good Luck,
    Allen
    UA Local 602
    A man who says that he can't learn anything in a class is exactly right.

  9. #9
    Join Date
    Jul 2007
    Location
    The Hot South
    Posts
    1,297
    You can also check the purity of the refrigerant by pumping down the unit, then manually run the condenser fans (no compressor), and see if the saturated refrigerant temp in the condenser matches the outside ambient temp.

  10. #10
    Join Date
    Feb 2006
    Location
    Atlanta,GA.
    Posts
    867
    I would pull charge replace driers w/ shell driers with valves on both sides and weigh charge in. I had some units a little older than that driers were stopped up and someone had overcharged unit

  11. #11
    Join Date
    Aug 2011
    Location
    fayetteville nc
    Posts
    18
    Sorry to get off subject, i have a unit with a bad baysensorsomthing19b. Can I switch to a conventional stat by switching from the numbers to the y r g w terminals. Or is there another control ill need.

  12. #12
    Join Date
    Aug 2011
    Location
    Los Angeles, CA
    Posts
    34
    If you have the UPC board with the #'s and the letters. Yes you can switch to a conventional stat. If you have the UPC board with no connections on it, then you would need the C.T.I board. (Conventional Thermostat Interface)

  13. #13
    Join Date
    Aug 2011
    Location
    fayetteville nc
    Posts
    18
    Thanks a lot. I have seen that cti but never knew what was for.

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