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  1. #1
    Join Date
    Nov 2003
    Location
    South Carolina
    Posts
    1,167
    I have a customer where my company installed a 404 compressor less than a year ago on a walk in freezer. The guy who installed it no longer works for me. I know he installed the right compressor because the old compressor is still sitting outside this restraunt and its an exact match. Ok well I got a call from the owner yesterday says freezer not getting cold enough...well I showed up not knowing what refer was in the unit because there is no listing on the condensing unit. I looked in the evap and it had a r12 txv in it...so i evacuate and put in mp66 which is a drop in r12...temp reallly never comes down that good. Well after looking in my computer at this job i find out 404a was put in by my prior employee so this thing has ran all night with mp66 in it....my question is how will this effect my compressor. Im going back today to replace the expansion valve to a 404a expansion valve and put 404 back in this system but have I ruined this compressor by letting r12 run in it over night? My past employee undoubtedly just changed this compressor with what he matched with that was already there unknowing that the expansion valve wasnt right.

  2. #2
    I think the compressor may be shot. When ya got there did you check it out before doing anything else.
    Hey cockroach, don't bug me!

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  3. #3
    Join Date
    May 2004
    Posts
    12,275
    The compressor should be ok... Take the long route and pump the system down using the compressor. See how far the compressor will pull itself down in a vaccum. With a 404 system... greater than 5" will work, more the better.
    Next, if the compressor shows good capacity on the valves with self vaccum... then change the oil on the compressor.. POE... re-install, add new liquid filter and suction drier.... pull good vaccum with pump.... recharge and be sure to set the superheat on the 404 TXP.. remember a 404 TXP bulb goes near the bottom of the suction line or at 4 to 5 o'clock... Good luck

  4. #4
    Join Date
    Jul 2003
    Location
    ALABAMA
    Posts
    230
    Your compressor should be ok. Just change out the valve and recharge the freezer. I hope it has a copeland compressor in it. They can take a beating.

  5. #5
    The old standby of self vacuum is no longer the reliable test it once was.

    The only thing a person can rely on today is the compressor curve published for this particular unit.

    Before saying this or that about a compressor curve chart.... first use one on a known good unit, which is running under it's regular load and everything is okay.

    This published chart is "da bomb".


  6. #6
    Join Date
    May 2000
    Location
    Monmouth Junction-NJ-USA
    Posts
    6,038
    Originally posted by lusker
    The compressor should be ok... Take the long route and pump the system down using the compressor. See how far the compressor will pull itself down in a vaccum. With a 404 system... greater than 5" will work, more the better.
    Damn what about all this literature that I read about not running a POE system in a vacuum. Hmmmmmmmmmm


    If you really know how it works, you have an execellent chance of fixin' er up!

    Tomorrow is promised to no one...

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