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major problems with new carrier system

our company installed the last part of march a new two ton carrier base model air conditioner with matched indoor cased evaporator coil. the unit ran fine for  a couple of months with no issues. at about the middle of june the unit would not cool. someone went out and replaced the txv because the unit would rung with good pressures, but after about 30 minutes of run time the unit would pump down, almost like there was a restriction, and there was no pressure drop across the liquid line drier. after a couple of days with the new txv the unit again would not cool, another tech went out there and found that the compressor was running with equalized pressures. the compressor was condemned, and replaced.after a couple of days, same symptoms the system was running fine for a bout thirty minutes with good pressures (135- 315 16 sh 20 sc) and had a 20 degree drop across the evaporator coil. this is a 410 a system. after a while of running the pressures dropped to a suction pressure of 80 and the subcooling went up to 40 degrees. it was almost like the txv had failed again, or there was a major restriction in the indoor coil. there is no temperature drop in the liquid or suction lines, and the lines are brand new and have been blown through with nitrogen several times. today someone was going out there to replace the evaporator coil entirely, and when he went to pump the unit down, the compressor pressures were equalized, the compressor was not pumping. the suction line was warm, and the discharge line was outdoor air temperature, not even warm to the touch. this would be the second compressor that has failed in this system. this is a very basic residential setup with only about 20' line set (3/4 and 3/8) with only about four foot of vertical change. the condenser is below the evaporator. we are at our ropes end with this system and it makes no sense what this system is doing. any ideas of what to do next would be much appreciated. short of asking our carrier salesperson for a new coil and condenser, we have hit a road block with everything that has been tried thus far. the unit info is as follows:

condenser carrier model 24abb324w330

evaporator carrier model cnpvp2417ala

compressor copeland model zp20kae-pfv-830

thanks to all


  • TechmanTechman Member Posts: 2,144
    edited June 2014

    Just a couple of things. What indoor/outdoor temps? 315psig head means about a 99* CondTemp which means about a 75* ambient or so; 135psig lo side means about a 47*EvapTemp which means about a 80-85* room temp. The SC should be about 8-10-12*.Is the SC # on the nametag? When the comp was running w/ equalized press and the discharge line was ambient temp , I think the comp  might not have been  running or if the comp was running and not pumping there would still be a little  amp draw and a little heat on the comp body. Did the weather get hot in the middle of June or so? Just incase the sudden drop of the lo side press is related to debris in the LL can a LLFD be installed at the evap?
  • zepfanzepfan Member Posts: 227
    The compressor is and was running

    The compressor is running and drawing low amps. How else

    Could the suction line get hot to touch unless something had come apart in the compressor and leaked hot gas into the low side of the system. If the compressor was offline bother the suction and discharge lines would be the same temp.
  • TechmanTechman Member Posts: 2,144

    Is there a CrankCaseHeater on the comp? 40* SC is a lot. Sounds like a "snapped" Scroll comp.
  • dondon Member Posts: 395
    edited June 2014
    The compressor

    If a scroll sound like it is going out on high temp and opening up the internal disk that bypass the refrigerant.The comp will run but not pump.Check your temp on the shell of the compressor.I would check the temp rise at the condenser and check the condenser motor to make sure it is turning the right rotation and rpms.

    What was the compressor discharge temps six inches coming out of the compressor? Is this a heatpump? If so I would also be checking temps at the reversing valve to make sure it not bleeding over.
  • dondon Member Posts: 395
    Make sure

    That they replace the drier. Even if there no temp difference at the drier I would replace it You would be better off checking the pressure at the drier instead of temps. I'll bet your problem at the condenser and more then likely that drier that was not replace bc their was no temp difference and that is always misleading when it come to driers.
  • zepfanzepfan Member Posts: 227
    Not a heat pump

    No this is not a heat pump, as I said in the original post it is straight ac. Yes the condenser fan motor is running in the right direction, and the scroll Astp that you are referring to is only on their three phase models. Our carrier salesperson has agreed to furnish a new condenser and evaporator. They don't have an answer for this either. We are going to change both and be done with it.
  • MattMatt Member Posts: 163
    moisture in the system

    If there is moisture in the system you could have ice forming in the TXV after a period of running.
  • TechmanTechman Member Posts: 2,144

    I think that moisture in an AC system will not freeze in the TXV because the EvapTemp is above freezing. Refrig and Freezers ,yes. The SGMI would show caution or wet,though.
  • RJRJ Member Posts: 483

    There is a chance that the rubber plugs on the end of the line sets were left in by accident, if any brazing was done on line set a partial restriction or floating debris in line set is a possibility. Something floating in the line set or evap coil may allow normal oper at startup and than cause a partial restriction which could cause compressor overheating and failure as the compressor may not cycle off on the low press control.  Or in one commercial job I worked on the liquid drier was installed incorrectly and the dessicant beads were found in the system
  • MagnehelicMagnehelic Member Posts: 63
    Service Bulletin

    There is a service bulletin out on Carrier 2 and 2.5 ton TXV's.......Danfoss brand......I have been out on several of the affected serials and most that I have looked at were fine. One last week was bad (not feeding properly) and needed to be changed out. I do not have access to the SB right now.......but this could be the culprit.
  • MagnehelicMagnehelic Member Posts: 63
    Updated DSB

    Carrier just released an UPDATED DSB dated 7-22 stating that

    "internal and field testing have confirmed that this is a start-up only issue and not caused by the txv or furnace coil. The txv is acting as a filter and capturing a "sticky" substance, which is causing the txv to operate improperly"

    I just wanted to be clear, as I have attested, I have been out on several of these now and only found one that was acting up. Replacing the valve resolved the issue.

    The DSB Covers the following model number 2 and 2.5 ton coils.




    For the serial number range 0114X - 2714X

  • unclejohnunclejohn Member Posts: 902
    edited July 2014
    So Carrier is blaming the field techs

    Zep said he ran new line set and I guess he pulled a vacuum. I also installed a new Carrier in March and changed out the TEV in June and it was a Danfoss.  It  just may be me, but doesn't the capillary tube on the bulb seem a little skimpy. It's roughly the size of thread. the replacement TEV was a Sporland and I doubt I'll be back under warranty with that valve. My valve was on a fv4cnf002t00 and was a 3 ton valve.
  • IronmanIronman Member Posts: 3,440
    Danfos TXV

    I just had to replace a Danfos TXV on a 3 ton, 16 seer Maytag that we installed six weeks ago. Could it be a bad batch of Danfos TXVs?
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • DonDon Member Posts: 184

    Here is the Carrier DSB Update that came out yesterday.......and the runor is that the sticky substance is a rust inhibitor used in reclaimed parts in Mexico used in building a certain component in the condensing units...........interesting eh??


    Number: DSB 14-0008 Issued: 7/3/14

    Revision: 8/22/14

    Title: Updated Interim Bulletin – Incorrect

    Super Heat for TXVs in 2 and 2.5 Ton

    Residential Furnace Coils

    UPDATE: Carrier has made significant progress in determining the root cause of the TXV issue described in the previous updates to this service bulletin. At this point, our testing indicates that the key issue is a change made to a rust inhibitor by a sub-tier supplier. We are in close contact with this supplier, which has since reverted back to using the previous rust inhibitor. Now that we have identified the substance that we believe is causing the issue, we have begun work to develop more efficient field service remedies. We will publish any updates to the field service recommendations as they become available.

    In the interim, continue to use the procedures detailed in this field service bulletin. Our testing confirms that these actions are effective to address the TXV high superheat issue.


    Residential Furnace Coils





    Effective immediately for serial number range: 4813X - 3314X

    The verification of affected date codes prior to week 33 of 2014 is still ongoing. If you have a unit with a TXV Super Heat issue outside of this date range (week 48 of 2013 through week 33 of 2014), please contact your DSM for consideration.


    Ongoing testing and reports from the field indicate that 2 and 2.5 ton Thermostatic Expansion Valves (TXV) currently used in the above listed furnace coil products may not maintain the correct Super Heat (SH) in certain situations.

    The end result can be a lack of cooling for the homeowner due to a frozen furnace coil and this has been diagnosed in the field by high SH and low suction pressures measured at the outdoor unit. Internal and field testing have confirmed that this is a start-up only issue and not caused by the TXV or furnace coil. The TXV is acting as a filter and is capturing a “sticky” substance, which is causing the TXV to operate improperly. Internal testing has confirmed that replacing a TXV after a field failure

  • dondon Member Posts: 395
    Hi Don

    And I assume when growing up I was the only one name don. LOL..Funny how carrier is blaming Mexico once again for their problem .But yet they continue to do biz in Mexico.The valve problem is across the board meaning that temp-star nordyne,trane,etc have all had txv issue.

    I am finding them not maintaining proper superheat to slam closed from not enough charge in the power head. Heck it is becoming such a norm that if the unit has a scroll compressor in it when you walk up to it you can hear the that noise that a scroll make when it running in vacuum.The last I have heard is that they think it could be an additive in the oil that sit in the compressor.

    Was out on one this morning air-temp heatpump low head,very low back pressure and, the scroll making that tinging noise. We cycle the reversing valve a couple of times from heat to cool and back to ac the superheat, subcool all fell right in line.  
  • IronmanIronman Member Posts: 3,440
    Tech Bulliten

    I just got a tech Bulliten from Emmerson acknowledging the sticky substance but saying they had not ID'd the cause and they were working with all manufacturers to find it. They acknowledged that it was industry wide and not limited to one manufacturer. I don't see how Carrier's bulliten lines up with that.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • icesailoricesailor Member Posts: 7,265

    Of interest might be that I had a new system installed to replace my old 1996 AC Rheem unit. It was replaced with a brand system that rhymes with railroad equipment.

    All went well with what I consider a quality install. Except that it didn't cool well when it got hot, and right out of the box, the blower was so loud that I had to turn up the TV just to her it when it runs. My energy bills went way up. There was never much, if any any temperature differential at the compressor or the AH.

    One Friday afternoon, after 5:00 PM, the system had a bowel movement in the bed. It was over 100 degrees outside. The installer came and got it going. I swear what it did is like what you are all describing, the valve closed and wouldn't open.

    I'm not an air head. This Railroad Unit has a FM Board (Freaking Magic) that runs the whole show. The Tech puled off the sensor wire that went to control the EEV valve through the FM board. Once he pulled the teeny weeny plug off the FM board, and cooled down the compressor, it ran fine. It even cooled better. He checked out the pressures with his FM gauges, and was puzzled that all was fine. There must be some issue because when he came with the parts, one thermostat wire was too short. They moved the FM board from a space where it could get air after the coil blown on it to a lower place where it was before the inlet to the blower. The Railroad Company didn't seem to understand that they had moved the location to another place so they insisted that the Tech had the right part. I showed the Tech this posting here. I mentioned this because he couldn't figure out why everything on his FM gauges said everything was fine, I told him from MY experience with FM boards on gas furnaces, that something was probably wrong with the board. That when he de-powered the thermostat to the board, the valve went fully open and worked. That it was probably a Normally Open Valve and the FM board, with info from the Thermostat, made it throttle, He checked the thermostat and said it Ohm'ed out correctly.That didn't compute to my Pea Brain. I suggested that he get another board. He did.

    When he finally got the parts, with the proper length theromstat wire, he also replaced the board. He wasn't taking any chances.

    Funny thing, with the new board, the AH works better, cool better, and the Locomotive is almost whisper quiet. Does that FM board also control fan speed? Because with the thermostat disconnected, the fan was much louder.

    I'm just pointing something out. I don't know nothin'. But it wouldn't be the first time that the poorly paid schmucks in the field had to do the engineering for the well paid suits.
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