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  1. #1

    system pumping down low ambient

    Hi out there, I have a walk in freezer prior company kept charging system 2 times a year without finding leak. I got called out pumped system up with inhert gas found leak fixed it and installed new drier. two days later got called out unit not cooling sight glass yellow. pumed system down installed another new drier and evacuated system for 5 hours, system worked well for 2 weeks. got called out today sight glass green full of charge system works during the day but at night when temp goes down to 50 degrees unit pumps down. turn system off for 20 min and turn it back on system runs normally can anyone advise

  2. #2
    Join Date
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  3. #3
    Join Date
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    Quote Originally Posted by gcmechanical View Post
    Hi out there, I have a walk in freezer prior company kept charging system 2 times a year without finding leak. I got called out pumped system up with inhert gas found leak fixed it and installed new drier. two days later got called out unit not cooling sight glass yellow. pumed system down installed another new drier and evacuated system for 5 hours, system worked well for 2 weeks. got called out today sight glass green full of charge system works during the day but at night when temp goes down to 50 degrees unit pumps down. turn system off for 20 min and turn it back on system runs normally can anyone advise

    Ok, gotta pick this apart, piece by piece...

    evacuated system for 5 hours
    Do you have a micron gauge? Did you use it?

    sight glass green full of charge system works during the day but at night when temp goes down to 50 degrees unit pumps down.
    Is this an outdoor unit? Does the unit have a headmaster control?

  4. #4
    yes condenser is on the roof of building and it does have a head master i thought that it was non condensables due to prior refrigeration company charging without fixing leak was on the low side vibration eliminator i fix it and change drier 3 times and evacuated 5 hours on last attempt now sight glass is green and system runs fine during that day but at night it fails. when i arrive in the mornind it is short cycling

  5. #5
    and yes 300 microns

  6. #6
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    Quote Originally Posted by gcmechanical View Post
    yes condenser is on the roof of building and it does have a head master i thought that it was non condensables due to prior refrigeration company charging without fixing leak was on the low side vibration eliminator i fix it and change drier 3 times and evacuated 5 hours on last attempt now sight glass is green and system runs fine during that day but at night it fails. when i arrive in the mornind it is short cycling

    Did you charge the system properly for headmaster operation?

    With a 300 micron vacuum, what makes you think non condensibles?

  7. #7
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  8. #8
    also forgot to mention when i took drier off for the first time the bottom line was full of oil could the system be oil bound

  9. #9
    thought it was non condensables before 300 microns. 404a refrigerant head pressure 200 suction starts at 50 psi and falles until low pressure cut out.

  10. #10
    new txv and now i think the system may be oil bound suction line is frosting but not all the way back to compressor

  11. #11
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  12. #12
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    Quote Originally Posted by gcmechanical View Post
    new txv and now i think the system may be oil bound suction line is frosting but not all the way back to compressor
    Have you taken any measurements other than pressure?

  13. #13
    you lost me i weighed in charge and cleared sight glass how do you charge for head master operation i did not know there was a differance for that tell me how

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