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Thread: 5 Ton Liebert

  1. #1
    Join Date
    May 2009
    Location
    Michigan
    Posts
    11

    5 Ton Liebert

    Model: PFCZ67A-AL3
    R-22
    3 Phase
    Dual receivers
    No cooling call. Compressor hotter than…. Low side 10psi High side 100psi Low amps on all legs 5.9-6.0
    Nameplate run amps is 10
    At first it looks like it has a leak …..low charge.
    I did find that the receiver pressure switch is open so that the receivers heaters haven’t been on.
    Outside temperature of 30 deg F

    My question is could during the off cycle most of the refrigerant has moved into the condenser because the heaters are off in the receivers. Than on start up the head pressure control is closed due to the low pressure in the receivers and its making it look like that its low on refrigerant because it’s bypassing all hot gas and starving the evaporator and no liquid is being let back into the system.

    I haven’t worked on any units with a Head Control so just trying to understand what I’m seeing here.

  2. #2
    Join Date
    Nov 2004
    Location
    up in the hizzy
    Posts
    1,375
    Quote Originally Posted by PowerPlant17 View Post
    Model: PFCZ67A-AL3
    R-22
    3 Phase
    Dual receivers
    No cooling call. Compressor hotter than…. Low side 10psi High side 100psi Low amps on all legs 5.9-6.0
    Nameplate run amps is 10
    At first it looks like it has a leak …..low charge.
    I did find that the receiver pressure switch is open so that the receivers heaters haven’t been on.
    Outside temperature of 30 deg F

    My question is could during the off cycle most of the refrigerant has moved into the condenser because the heaters are off in the receivers. Than on start up the head pressure control is closed due to the low pressure in the receivers and its making it look like that its low on refrigerant because it’s bypassing all hot gas and starving the evaporator and no liquid is being let back into the system.

    I haven’t worked on any units with a Head Control so just trying to understand what I’m seeing here.
    Interesting scenario, very unlikely to happen.

  3. #3
    Join Date
    Jan 2010
    Posts
    6,058
    Is there a sight glass ?

  4. #4
    Join Date
    May 2009
    Location
    Michigan
    Posts
    11
    Yes it has a sight glass/float on each receiver, not showing a level. Valdelocc your right after thinking and checking a little closer it has a check valve between the receivers and condensers, so can't migrate back to the condenser.

    FYI,pulled the charge and about 15 lbs. low. The relief valve on the receiver was leaking.

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