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  1. #1
    Join Date
    Jun 2005
    Posts
    188

    Compressor out on LRA after new install

    Removed a 3 ton lennox r22 split system on saturday and replaced it with a luxaire 3 ton r410a system. There was no place to run a new line set so we flushed it with par flush and nitrogen and did a bunch of leak checks. We installed the A/H with a TXV and installed the new condenser, pulled a 300micron vac that held, opened the valves and added 3.5lbs of refrigerant. The unit was running PERFECTLY: 20 degree split, 11 degrees of subcooling, no problems what so ever.

    So i decide to cycle the white rodgers thermostat we installed as well. Turn the temp down, let the unit shut off and then turn it back on.....The CFM comes on but not the compressor. Ok so i clamp up my amp meter, turn the disconnect back on and check it out: The compressor starts pulling LRA. At this point im pissed, so I shut the stat off again and wait a few minutes. The condenser comes on and is working perfectly!!!! I shut it off again and turn it back on.....compressor out on LRA again. I did this a few times and got the same results everytime.

    What could be causing this problem? I was thinking that maybe the pressures inside the compressor are not having time to equalize which could be causing the compressor to pull LRA....Tell me what you think.

  2. #2
    Join Date
    Oct 2007
    Location
    Hallandale Beach, FL.
    Posts
    434
    Is it a recip or scroll comp? If recip is there a start kit on it?
    I miss you mom and dad.

  3. #3
    Join Date
    Jun 2005
    Posts
    188
    Its a scroll.

  4. #4
    Join Date
    Jun 2005
    Posts
    188
    The damn stat doesnt have a 5min delay. I thought all stats had that

  5. #5
    Join Date
    Jul 2012
    Location
    Kansas
    Posts
    78
    Is the time delay working? The condenser shouldn't restart on a call for cool for about 5 minutes.

  6. #6
    Join Date
    Jul 2012
    Location
    Kansas
    Posts
    78
    Most new condensing units have delay built into the board. I'm not sure about Luxaire though. rtfm

  7. #7
    Join Date
    Mar 2009
    Posts
    69
    let it equalize

  8. #8
    Join Date
    Jun 2012
    Location
    East tx
    Posts
    164
    Most condensers don't have a board for time delay. Time delay cones from stat which this one doesn't have. Almost any system that tries to start right after being turned off won't nothing is wrong with the equipment. Just needs tine to equalize between cycles.

  9. #9
    Join Date
    Jun 2005
    Posts
    188
    thats what i figured, thanks for your help guys

  10. #10
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,596
    Quote Originally Posted by Crazecodyk View Post
    Most condensers don't have a board for time delay. Time delay cones from stat which this one doesn't have. Almost any system that tries to start right after being turned off won't nothing is wrong with the equipment. Just needs tine to equalize between cycles.
    Agreed. If you want you could add a time delay, there's usually plenty of room in the control cabinet.

  11. #11
    Join Date
    Jun 2007
    Location
    Greenwood Indiana (Indianapolis)
    Posts
    420

    Lightbulb 410A

    [QUOTE=dcx516;14166851]Removed a 3 ton lennox r22 split system on saturday and replaced it with a luxaire 3 ton r410a system. There was no place to run a new line set so we flushed it with par flush and nitrogen and did a bunch of leak checks. We installed the A/H with a TXV and installed the new condenser, pulled a 300micron vac that held, opened the valves and added 3.5lbs of refrigerant. The unit was running PERFECTLY: 20 degree split, 11 degrees of subcooling, no problems what so ever.

    Not sure on length of line set but 3.5 pounds seems like too much too me. We usually are adding ounces to ours, not pounds.

    Change out the stat, or buy a time delay relay.
    As iron sharpens iron so one man sharpens another Proverbs 27:17 NIV84

  12. #12
    Join Date
    May 2010
    Posts
    17
    Recently, install crew added a txv to a lennok coil that would supposedly bring the SEER rating up from 14 to 16. After install, i get called out for servvice and the unit is pulling LRA. (Lennox by the way). Scroll compressor. I added a hard start to the unit, and have not been called back this summer. That was in June.

  13. #13
    Join Date
    May 2004
    Location
    Salt Lake City/Tooele
    Posts
    2,509
    I would assume that the new condenser with R410a came factory charged? So the addition of 3 pounds and 8 ounces of to the new system would tend to tell me that you have a hell of a long lineset. If this is the case, you may need to touch base with the manufacturer as for what in addition may be required to operate this unit. Possibly hard-start kit, liquid line solenoid, etc. Many manufactures have Refrigeration Piping Manuals to make sure that you are not only properly sizing the piping, but also following good piping practices and adding necessary components to help the compressor stay within it's operational envelope.

    Like said earlier 3.5 pounds of R410a seems like a lot. It is VERY EASY to overcharge a R410a system and if per chance this condensing unit uses aluminum micro-channel outdoor condenser...you could be in a whole world of hurt.

    As with everyone else....a time delay is a MUST.

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