Page 1 of 4 1234 LastLast
Results 1 to 13 of 44
  1. #1
    Join Date
    Jan 2020
    Location
    Portland Oregon
    Posts
    90
    Post Likes

    Compressor Swap odd behavior

    Today I changed out a Copeland scroll ZP49K5E-FPV compressor. Itís on a 5 ton Goodman AC only split system with condensing unit 18 feet below air handler & 65 total feet of lineset. I put a liquid line solenoid just after liquid service valve & wired it in parallel with contactor. New filter drier after LLS & evacuated to 330 Microns holding.

    When I charged the system, I added 80% of factory nameplate charge in suction service port. I didnít have the LLS energized so I didnít add through liquid line.

    I stutter started the compressor (bump on 2 seconds, wait 10 seconds, bump on 4 seconds, wait 15 seconds, bump on 10 seconds, wait 30 seconds, then let equalize) and it started up after that no issue. Ran it for 2 minutes watching high side go up to normal operating pressure of 225PSI and low side drop SLOWLY 150 PSI (52degree evaporator). The inside temp was only 63 degrees.

    Iím assuming there was a whole lot of liquid built up in the suction line and that the compressor was dealing with it little by little. I would expect a much lower suction pressure with 63 ambient return air. The liquid line was warm and I could feel it flowing liquid. Compressor amps were at 23 (RLA is 25).

    Why would suction pressure not drop more considerably? You think itís a buildup of liquid in the suction line working itís way through?


    Sent from my iPhone using Tapatalk

  2. #2
    Join Date
    Apr 2020
    Location
    Garner NC
    Posts
    541
    Post Likes
    Before you put in the new compressor did you fully blow out/purge the line set/unit/condenser/evap of any excess oil from the old compressor with nitrogen?

  3. #3
    Join Date
    Jan 2020
    Location
    Portland Oregon
    Posts
    90
    Post Likes
    Thread Starter

    Compressor Swap odd behavior

    Yes. I unsweated the suction line off compressor & let nitrogen flow through liquid service valve at TEST pressure on my reg. Let nitrogen flow for 45 seconds holding my thumb over compressor suction port & periodically over the suction line that came off of compressor to build pressure up & release.

    Not a whole lot came out.


    Sent from my iPhone using Tapatalk

  4. #4
    Join Date
    Jun 2013
    Posts
    55
    Post Likes
    Yes l would wait now
    Itís better to charge thru LL cause you cut thru piston or txv when flowing
    That solenoid wonít allow unless you call from tstat without the quick disconnect 240 v


    Sent from my iPhone using Tapatalk

  5. #5
    Join Date
    Jan 2020
    Location
    Portland Oregon
    Posts
    90
    Post Likes
    Thread Starter

    Compressor Swap odd behavior

    Will all that liquid in the suction line work through system eventually?

    Sent from my iPhone using Tapatalk

  6. #6
    Join Date
    Aug 2008
    Location
    Hibbing, MN
    Posts
    823
    Post Likes
    First off, I use a solenoid valve magnet to open the valve when it’s not convenient or possible to energize the valve. Secondly, liquid in the suction line is never a good thing. I washes oil off the bearings and can wreck the valves in the compressor. Try pumping the system down by de-energizing the LLSV or closing the liquid line valve. If the system doesn’t pump down, you might want to think about doing another compressor change.
    If God didn't want us to eat animals... He wouldn't have made them out of MEAT.

  7. #7
    Join Date
    Dec 2014
    Posts
    3,046
    Post Likes
    "When I charged the system, I added 80% of factory nameplate charge in suction service port. "

    Uh oh! Never dump liquid into the low side.
    Being a scroll, you might have gotten lucky , and theres no damage, but with that low head pressure, and high amps, it's not looking good. Dragging bearing maybe.
    225psi indicates a high 50s ambiant for 410a.
    Interested what the superheat was, and the discharge temp would be good to know too. I'm thinking it was around 100f, as you were likely pumping liquid .

    Sent from my SM-G950U using Tapatalk

  8. #8
    Join Date
    Aug 2008
    Location
    Hibbing, MN
    Posts
    823
    Post Likes
    Oops. Missed the scroll part. No valves to blow out. Only bearings to wash out.
    If God didn't want us to eat animals... He wouldn't have made them out of MEAT.

  9. #9
    Join Date
    Jan 2020
    Location
    Portland Oregon
    Posts
    90
    Post Likes
    Thread Starter
    Iím going to go back out there in the next couple days to hook up my field piece probes to the system and my field piece charging jacket to get everything dialed in. Copeland scrolls are pretty bulletproof so Iím crossing my fingers. System wonít get any real runtime for 4 more days.

    Going forward I will always charge through liquid line with solenoid energized if applicable.


    Sent from my iPhone using Tapatalk

  10. #10
    Join Date
    Jan 2020
    Location
    Portland Oregon
    Posts
    90
    Post Likes
    Thread Starter
    Quote Originally Posted by icy78 View Post
    "When I charged the system, I added 80% of factory nameplate charge in suction service port. "

    Uh oh! Never dump liquid into the low side.
    Being a scroll, you might have gotten lucky , and theres no damage, but with that low head pressure, and high amps, it's not looking good. Dragging bearing maybe.
    225psi indicates a high 50s ambiant for 410a.
    Interested what the superheat was, and the discharge temp would be good to know too. I'm thinking it was around 100f, as you were likely pumping liquid .

    Sent from my SM-G950U using Tapatalk
    It was 52 degrees ambient - condenser fan speed is controlled by electronic low ambient controller (slows down fan).


    Sent from my iPhone using Tapatalk

  11. #11
    Join Date
    Aug 2008
    Location
    Hibbing, MN
    Posts
    823
    Post Likes
    Buy one of these...
    Attached Images Attached Images  
    If God didn't want us to eat animals... He wouldn't have made them out of MEAT.

  12. Likes EnergyOasis liked this post.
  13. #12
    Join Date
    Apr 2003
    Location
    Maple Grove, MN
    Posts
    3,375
    Post Likes
    Quote Originally Posted by EnergyOasis View Post
    I’m going to go back out there in the next couple days to hook up my field piece probes to the system and my field piece charging jacket to get everything dialed in. Copeland scrolls are pretty bulletproof so I’m crossing my fingers. System won’t get any real runtime for 4 more days.

    Going forward I will always charge through liquid line with solenoid energized if applicable.


    Sent from my iPhone using Tapatalk
    Quote Originally Posted by EnergyOasis View Post
    It was 52 degrees ambient - condenser fan speed is controlled by electronic low ambient controller (slows down fan).


    Sent from my iPhone using Tapatalk
    Why would you think you would need to use a "charging jacket" if the unit already has a condenser fan speed control?

    Why were you replacing the compressor if "Copeland scrolls are pretty bulletproof"?

    As others have said you should have never have dumped all of that liquid into the suction side. What were you thinking there? When I was going through tech school and just starting out it was hammered into me that liquid refrigerant going to a compressor was bad. Did no one ever tell you that liquid in the suction line was a dangerous thing that you had to be careful of?

    Sorry for yelling at you. With the numbers you have provided, I'm guessing you got lucky and didn't wreck your compressor. What type of metering devise does this system have and what is your subcooling and superheat?
    If at First You Don't Succeed, Skydiving Is Not for You.

  14. Likes Unlimited1 liked this post.
  15. #13
    Join Date
    Jan 2020
    Location
    Portland Oregon
    Posts
    90
    Post Likes
    Thread Starter
    Quote Originally Posted by ammoniadog View Post
    Why would you think you would need to use a "charging jacket" if the unit already has a condenser fan speed control?

    Why were you replacing the compressor if "Copeland scrolls are pretty bulletproof"?

    As others have said you should have never have dumped all of that liquid into the suction side. What were you thinking there? When I was going through tech school and just starting out it was hammered into me that liquid refrigerant going to a compressor was bad. Did no one ever tell you that liquid in the suction line was a dangerous thing that you had to be careful of?

    Sorry for yelling at you. With the numbers you have provided, I'm guessing you got lucky and didn't wreck your compressor. What type of metering devise does this system have and what is your subcooling and superheat?
    The ICM325HN condenser fan speed control only gets pressure close to where it should be - I would prefer see sub cooling & superheat when simulating a 95 degree day (~395 Psi @ 20degree condenser to outside air split).

    The system I was working on had a bad leak in bottom of condenser coil so the Copeland scroll that I was replacing had run for who knows how long without refrigerant. I tested winding resistance against Copeland mobile app specs on that compressor...shorted start winding.

    Iím gleaning better practices from all your wisdom & I greatly appreciate the input. The Journeymen that work for same day job company as I do are more parts changers than meticulous servicemen...

    Knowing that there may be liquid built up in suction side, would it be best to recover the charge, revacuum, and add in liquid side? What happens to the oil that is washed out of compressor by the liquid it has dealt with?

    Also, does having a liquid line solenoid at condensing unit help prevent liquid migration back to compressor? That was my thought


    Sent from my iPhone using Tapatalk

Page 1 of 4 1234 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Contracting Business
HPAC Engineering
EC&M
CONTRACTOR