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  1. #1
    Join Date
    Mar 2004
    Location
    midwest
    Posts
    958

    Lightbulb

    Have a 70-ton flowtronic and we have a b circuit compressor on its way out again, like (3rd in a year)OUCH. Here is what we found so far; when the unit sheds its load and cycles from 3rd stage to 2nd it pumps out the b compressor. Well intermittedly keeps pumping out the compressor into a vaccume condition, causing bad vibration and internal damage. It was suppose to pump out to 10F below suction sat temperature....We have monitored the unit for 2 days and have caught only it 3x doing this. Otherwise the unit runs and checks out good. All thermistors check out OK. EXV was tested and it works. All indications are the main board? reluctantly we say this but Carrier has no insight in their stock troubleshooting info. Anyone else have a similar problem
    An astronaut stuck in space was asked by a reporter, "How do you feel?"
    "How would you feel," the astronaut replied, "if you were stuck here, on top of 20,000 parts each one supplied by the lowest bidder?"

    "do it right or do it twice"

  2. #2
    Join Date
    Feb 2003
    Location
    Wichita Ks
    Posts
    1,473
    i have had new flowtronics go into a vacuum on pump down and no problems. 3 compressors in a year. time to open up the compressor and find out why. who rebuilding the compressors? there is a lot of rebuilders that do a lousy job. also make sure you log all readings on start up such as oil pressure, discharge temp, motor temp, total superheat, oil temp and so on.

  3. #3
    Join Date
    Jan 2005
    Posts
    604
    Ah, never mind.

    Good luck.

    [Edited by r718 on 05-10-2005 at 11:00 PM]

  4. #4
    Join Date
    Mar 2004
    Location
    midwest
    Posts
    958
    Compressor were remanufactured from Carlyle. Last compressor went bad from oil washout. No oil in compressor damaged main bearing and internals. We found after the compressor replacement all of the oil logged in the evap. Ran new and removed the excess oil after it came back. I agree that the pump out cycle may go into vac for short time but when it keeps on running well into the vac and after the refrigerant is pumped out its not a good thing...
    Plus, when it is in this stage the compressor vibrates real bad, sounds like a machine gun.
    An astronaut stuck in space was asked by a reporter, "How do you feel?"
    "How would you feel," the astronaut replied, "if you were stuck here, on top of 20,000 parts each one supplied by the lowest bidder?"

    "do it right or do it twice"

  5. #5
    Join Date
    Jul 2001
    Posts
    310
    I know you say you have checked the thermistors but most every problem we have with our Flowtronic is thermistor related. Did you check to see if the thermistor changed ohm value at an adaquate rate. We had one the other day that did not seem to update as quick as the others. This caused on compressor to flood at times because it did not send the proper message back to the board fast enough for the exv to adjust properly. Changed the thermistor and everything is working fine again. Just a thought
    I'm only working because it's not duck season!!!!!!!!!!

  6. #6
    Join Date
    Oct 2004
    Posts
    1

    Thumbs up Compressor problems

    Check you starter contacts & pumpdown solonoid.
    Had this problem & found starter contacts sticking sometimes due to coil on starter swelled up.

  7. #7
    Join Date
    Jan 2005
    Location
    Houston TX
    Posts
    874

    Hmm

    I had an identical problem with a larger Flowtronic and I was told the same rigamorrow A) change processor B)change motherboard and processor C) change compressor out and loss of chacge switch. As this machine was still under Carrier warranty we did as requested. All sensors where correct temp, voltage drop and resistance. On a fluke I swapped the evaporator refrigerant sensor from one circiut to the other (desperate time desperate measures) and the other circuit pulled down into a deep vacuum on shut down. I changed both sensors and the problem disappeared. I hope this helps you.

    ga1279

  8. #8
    i would double check suction and return gas sensors and make sure there not out of calibration. do u use flotronic monitor.

    also flotronic is spelled flotronic not flowtronic.

  9. #9
    Join Date
    May 2001
    Location
    Western Wa
    Posts
    1,833

    Talking flotronics are responsible for a lot of bald technicians

    And I am living proof.

    As much as I hate to be a parts changer, change the thermistors. Usually the barrel sensor for that circuit when they start having wierd superheat symptoms. I had an EXV stick once, and the EXV wiring plug rot off due to sweating, but almost always it's a thermistor that you can't spot with the quik-chek or even a DMM.

    Isn't technology wonderful?
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    God Bless the USA

  10. #10
    Join Date
    Mar 2004
    Location
    midwest
    Posts
    958
    the compressor was still under warranty, tech converted the b compressor to an unloader and changed the setting on the new board to lead and lag control. Will advise on thermistor change out, Thanks for the INFO. I still can't understand how a thermistor can intermittend stop working? I thought they either work or don't? It seems you can take the Carrier tech lit and throw it out the window as far as checking sensors go...Just my 2 cents.
    An astronaut stuck in space was asked by a reporter, "How do you feel?"
    "How would you feel," the astronaut replied, "if you were stuck here, on top of 20,000 parts each one supplied by the lowest bidder?"

    "do it right or do it twice"

  11. #11
    Join Date
    Jan 2005
    Location
    Houston TX
    Posts
    874

    HVAC DOCTOR

    Please don't asked about sensors as I totally agree but in my situation they both checked out good, yet the lead circiut would continue to pump down to 27" of vacuum. When I switched the sensors around in the entering evaporator liq. ref. wells, the problem went to the other circuit (see previous thread) I have had bad sensors sit in the van and suddenly become accurate again, go fiqure..........

  12. #12
    Join Date
    Dec 2002
    Posts
    9,871

    The sensors

    Are POS. Have changed over 100 during career and have always soved problem. As stated, the contactor coild be sticking.

  13. #13
    Join Date
    Feb 2003
    Location
    Wichita Ks
    Posts
    1,473
    2 years ago i went out on one the customer could not keep a compressor in it very long. i replaced the compressor and watched it operate. it did ok but when it shut off and another compressor came on and the fans started to stage in the compressor that was suppose to be off came on. traced out wiring and found a field installed jumper between 2 fan contactors. the problem was one of the fan contactors was wired to come on with the compressor that was off. so when the compressor was suppose to be off it would be on when the other circuit was up and running. the micropressor had to control of it. the jumper was added because the maintance people didnt want to wash the coils. you never know what someone else might do to a system before you are there and they wont admit to anything.

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