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  1. #1
    Join Date
    Jul 2006
    Posts
    13

    401B retrofit for LT R12 system (toast)

    Started with a 4x8 walk-in freezer with a Copeland semi hermetic self contained 1 hp unit on roof of the box, stuck in the hottest corner of a kitchen with no fresh air flow to speak of. Ambient temp 90+ upon arrival I checked system out, it was dead empty. I pressurized with nitrogen and found a bad leak at the high side service valve stem, it had no cap. I caped it and used the receiver service valve the system held vac nice. Original factory tag showed 80oz R12, I had a fresh tank of MP66 and a new container of AB oil in the truck, got the ok from the owner to proceed. After changing the oil and pulling another vac I proceded to add 85% of the original system charge with 401B my first mistake was I added in gas instead of liquid (thought I had a dip tube in the tank) ok, I recovered the gas and added 4.25 lbs of liquid to the high side. I started the system up all looked and sounded fine pressures 8 and 225 after 30 mins box was down to 45deg and heading down, oil level held good 1/3 + glass. Suction side line temp seemed high I had not check superheat . Stepped out for lunch got back bit later compressors sounded bad and locked up just as I returned, box never got below 45 deg. My question is if I let 4lb of gas out of the 401b , what is left in the tank, is it still good or is this tank junk. Could the reason of the failure have been not enough cooling getting back to the compressor because of an imbalance of the refrigerant blend the compressor appeared to be overheated?

  2. #2
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,478
    Letting out 4 lbs of vapor from a 30 lb blend is sure to mess up the mix to some degree. How much? I don't know the answer to that, but it can't be good.

    If you recover the first charge and that which is remaining in the drum into a clean recovery tank you should get your blend back.

    The other question here is did this compressor mechanically seize or did it just trip the overload protector? I'm guessing it trip the OL because this is likely a KALB-0100 and in my experience with these on MP66 they tend to run real close to the trip point during pulldown and post defrost. One of my first R12/MP66 conversions was a KALB-0100-TAC that never did run well afterward, at least until I added a water-cooled condenser with a regulating valve...a la the air & water CU's of days gone by. The owner didn't like the higher water bill but it worked.

    If it definitely seized, I really doubt it had to do with the refrigerant. It's more likely it was damaged from before you got involved.

    However, with the rapidly rising cost of this R401B (and no decent substitute on the horizon) and since this condensing unit is probably over 20 years old, I think seriously about installing a new R404A hermetic LT unit on this system before getting too deep into it.

    Oh....Welcome to the site!
    Last edited by icemeister; 07-21-2008 at 04:57 PM.

  3. #3
    Join Date
    Jun 2008
    Location
    South Carolina
    Posts
    36
    Did the unit have a functioning low pressure switch? If not, how long did it run with no refrigerant? I'm no chemist but I was always told that you could cause problems with the remaining refrigerant if you pull to much vapor off the top of the cylinder made from blends. It's hard to say exactly what caused the failure, taking apart the compressor may give you some indication why it failed.

  4. #4
    Join Date
    Jul 2006
    Posts
    13
    No low side switch on unit, If I made the mistake I will offer to repair this unit at no charge, so that will leave me with two problems, where can I find a referance chart to match this old Copeland unit for a replacement, and I now have 26 lbs of MP66 I may have damaged, is there any way to tell if it is still good? Do I take the chance...

  5. #5
    Join Date
    Sep 2005
    Location
    florida
    Posts
    5,514
    Quote Originally Posted by nrowey View Post
    No low side switch on unit, If I made the mistake I will offer to repair this unit at no charge, so that will leave me with two problems, where can I find a referance chart to match this old Copeland unit for a replacement, and I now have 26 lbs of MP66 I may have damaged, is there any way to tell if it is still good? Do I take the chance...
    Ice or powell will be along soon to give ya a match.
    I love the smell of phosgene first thing in the morning:

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  6. #6
    Join Date
    Jun 2005
    Location
    Las Vegas NV
    Posts
    1,152
    Quote Originally Posted by nrowey View Post
    where can I find a referance chart to match this old Copeland unit for a replacement,
    nrowey,

    What is the model of the Copeland unit or compressor? The model number of the evap would also be beneficial as would the line sizes.

    powell

  7. #7
    Join Date
    Jun 2008
    Location
    South Carolina
    Posts
    36
    Be sure to install a high/low pressure switch on your new unit. I also like to install a time delay relay to prevent short cycling of the compressor. Chances are pretty good that the compressor was damaged before you were ever called. Operating the compressor with out refrigerant is sure cause for failure.

  8. #8
    Join Date
    Sep 2007
    Location
    NH
    Posts
    1,213
    Quote Originally Posted by nrowey View Post
    No low side switch on unit, If I made the mistake I will offer to repair this unit at no charge, so that will leave me with two problems, where can I find a referance chart to match this old Copeland unit for a replacement, and I now have 26 lbs of MP66 I may have damaged, is there any way to tell if it is still good? Do I take the chance...


    Ice already mentioned it.

    You would have to recover the ref in the sytem and add the rest of the tank plus the gas that you already recovered in to a clean tank.

  9. #9
    Join Date
    Jun 2008
    Location
    South Carolina
    Posts
    36
    I've also had problems with KALB-0100 after converting. I had to install crankcase pressure regulators on some of them. Coming out of defrost on a hot day would always trip it.

  10. #10
    Join Date
    Jul 2006
    Posts
    13
    I will get numbers of the unit and post ASAP
    Thanks for your help.

  11. #11
    Join Date
    Jul 2008
    Location
    Denver, CO
    Posts
    4,229
    I would say you had nothing to do with it, if their was a leak on the service valve it proably lost a lot of oil out of the system over the years and running without refrigerant probably ruined what was left of the oil in the system.

  12. #12
    Join Date
    Sep 2002
    Posts
    13,501

    Why not mix it back together?

    Just pump what you recovered and what it still in the disposable cylinder into a recycle cylinder and label it. Throw away the disposable and let the added weight of carrying that recycle cylinder up and down ladders teach you a valuable lesson. <g>

    PHM
    ---------


    Quote Originally Posted by nrowey View Post
    Started with a 4x8 walk-in freezer with a Copeland semi hermetic self contained 1 hp unit on roof of the box, stuck in the hottest corner of a kitchen with no fresh air flow to speak of. Ambient temp 90+ upon arrival I checked system out, it was dead empty. I pressurized with nitrogen and found a bad leak at the high side service valve stem, it had no cap. I caped it and used the receiver service valve the system held vac nice. Original factory tag showed 80oz R12, I had a fresh tank of MP66 and a new container of AB oil in the truck, got the ok from the owner to proceed. After changing the oil and pulling another vac I proceded to add 85% of the original system charge with 401B my first mistake was I added in gas instead of liquid (thought I had a dip tube in the tank) ok, I recovered the gas and added 4.25 lbs of liquid to the high side. I started the system up all looked and sounded fine pressures 8 and 225 after 30 mins box was down to 45deg and heading down, oil level held good 1/3 + glass. Suction side line temp seemed high I had not check superheat . Stepped out for lunch got back bit later compressors sounded bad and locked up just as I returned, box never got below 45 deg. My question is if I let 4lb of gas out of the 401b , what is left in the tank, is it still good or is this tank junk. Could the reason of the failure have been not enough cooling getting back to the compressor because of an imbalance of the refrigerant blend the compressor appeared to be overheated?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  13. #13
    Join Date
    Jul 2006
    Posts
    13
    I just got the numbers BAL0100CAB001 top mount unit. looking to get replacement semi compressor.

    Thanks for Help

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