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  1. #1
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    Oil Foaming Compressor OL

    I recently changed out a 70/5 run capacitor and condenser fan motor on a 5 ton Goodman AC split system. The condensing unit is 15 feet lower than the air handler and had a three wire 5-2-1 hard start kit & electronic (thermistor) low ambient condenser fan control, as well as crankcase heat strapping.

    The customer had pulled the disconnect on the unit prior to the repairs I made. After starting the unit up the compressor (scroll) & condenser fan started up & low ambient fan controller started ramping the fan speed down. Compressor was definitely experiencing oil foaming & after 3 min went off on thermal OL.

    My question is will the oil make its way back to compressor (coldest point in system)? I’m concerned that the crankcase heat was off & that the compressor sounded like it was slugging a bit before it shut down on OL.

    How likely is oil foaming to kill a Copeland scroll compressor?

  2. #2
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    Why was the unit started without energizing the heater even for a few hours?

    Why did you continue to run when by the sound you knew there was an issue?

    Will it come back yes if the pump can live that long!

  3. #3
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    Customer was in hurry to leave the business & I didn’t have a few hours to run crankcase heat. I disabled the control voltage to contactor after OL happened. Will be returning at the end of the day today to re install control voltage to contactor, that way crankcase heat has time to work.

    Going forward I will insist on running crankcase heat for full day before re-starting system. I’m hoping & praying that oil makes its way back to compressor & it restarts.

  4. #4
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    Not likely to kill a scroll in that circumstance.

    How were you able to determine that the "compressor was definitely experiencing oil foaming" ?

    How is the oil foaming related to the O/L opening?

    Why weren't you monitoring the compressor amp draw during an initial startup?

    PHM
    ---------





    Quote Originally Posted by Nate Fryer View Post
    I recently changed out a 70/5 run capacitor and condenser fan motor on a 5 ton Goodman AC split system. The condensing unit is 15 feet lower than the air handler and had a three wire 5-2-1 hard start kit & electronic (thermistor) low ambient condenser fan control, as well as crankcase heat strapping.

    The customer had pulled the disconnect on the unit prior to the repairs I made. After starting the unit up the compressor (scroll) & condenser fan started up & low ambient fan controller started ramping the fan speed down. Compressor was definitely experiencing oil foaming & after 3 min went off on thermal OL.

    My question is will the oil make its way back to compressor (coldest point in system)? I’m concerned that the crankcase heat was off & that the compressor sounded like it was slugging a bit before it shut down on OL.

    How likely is oil foaming to kill a Copeland scroll compressor?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  5. #5
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    In that situation you should have "stutter started" the comp. Energize the comp for 3-4-5 seconds,then shut down the comp. Do that 3-4-6 times, saves the life of a comp everytime. That stutter start is how the new-ish Copeland EUC works. Save that comp, don't kill one!

  6. #6
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    Thread Starter
    I will be running crankcase heat for 4 hours prior to starting up the 3rd system, as well as running heat gun on compressor for 15min or so. Will pay close attention to compressor amp draw & pressures during the run.
    As for ”stutter-starting”, am I to run compressor for 3 seconds, let equalize, 4 seconds, let equalize, then 5 seconds, let equalize? I am open to all advice & grateful for the wisdom given. Adopting & adhering to best practices is my goal.

  7. #7
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    I believe you're over-thinking this and panicking unnecessarily over the cold startup and subsequent shutdown on internal overload.

    Copeland's Application Engineering Bulletin AE4-1331 R8 which covers R410A 3-5 ton A/C scrolls, states in the section on crankcase heaters on p.8 that a CC heater is recommended for compressor over the system charge limit in Table 4 on p.25 and required for compressors over 120% of that limit. For a nominal 5-ton ZP61K5E, the largest in that model series, the table limit is 10 lbs. So with a system under 10 lbs of R410A Copeland says you technically wouldn't need crankcase heat as the compressor is capable of handling that much liquid in a cold start scenario.

    https://climate.emerson.com/online-p...blication=1331

    Further in that section, it's stated that it's normal for the compressor to shut down on overload several times during such cold starts. So again, no need to get excited.

    FWIW...Looking at Goodman's condensing unit specs for 13 SEER thru 18SEER, their standard charge amount runs from 6 lbs through just under 10 lbs for their 5-ton units.
    Last edited by icemeister; 01-14-2020 at 09:34 AM.

  8. #8
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    As icemeister has noted, I've seen many smaller ac scrolls without crankcase heaters.
    It probably was the denser refrigerant in a cold environment that raised the amps enough to trip the internal overload.

  9. #9
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    Thread Starter
    Thank you for your help & informative response. I will be starting up the last Goodman VSX13060BA this afternoon after crankcase heat has ran for 4hours. Will respond with how it goes.

  10. #10
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    How did you know the oil was foaming?

    sounds like a residential type unit which wouldn't have a SG or a receiver or an oil sump with an oil level gauge where it's normally observed?

    Just curious, is there some magic way to know if it's foaming?

  11. #11
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    I assumed oil foaming due to flooded start. It concerned me because the compressor shut off. The units all have functional 5-2-1 hard start kits & crankcase heat now.

  12. #12
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    Factory start parts or after market?

  13. #13
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    Thread Starter
    Factory (Goodman part number)

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