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  1. #1
    Join Date
    Oct 2011
    Location
    midwest
    Posts
    58

    Possible restriction or bad compressor

    I dont want to be parts changer. I would like to get this the fist time I go back to this service call on monday.

    Call from Philips 66 Gas Station. Reason for call: Walk in cooler warm. I will try to give you guys as much details as I can....

    When I arrived the first thing i check was my temp inside the walk in cooler. Temp is 65. I got two evap and each one got txv on it. Now that I know what I got inside I went outside to see my condensor. Everything is working but my suction line is not cold and my discharge is warm. Put my gauges on and found my suction at 20 psi and discharge at 120 psi. Looked at my sight glass and found it with lot of bubbes. I got excited I thought I know it was low on refrigerant. Put some R22 and watch my sight glass until it got all clear....My discharge pressure was still at 120..... So know I think I got restriction somewhere on my discharge line.. Hmm maybe txv or filter drier or maybe head master.... Checked my amps.. Three phase.. Check each wire to the compressor. one is 12. two 11 three 5....Hmm What else can i check.. oh yes let me see that txvs.. Put all the refrigerant in my reciver and checked my txvs.. I found the screens on txv half black and some small particals in it... Used my nitrogen to clean them out.. I can see through the screen. I think they are okay...Closed everything up. Recover all the refrigerant and pressurized it with nitrogen. NO LEAK. Pulled vaccum to 400 microns. New filter and refrigerant.... Charged the unit again.. Same issue my discharge is at 120 psi... What else can I do when I go back.. Possible kinck somewhere?? Compresor is bad... Never had to change headmaster before. Could this be possibilty??

  2. #2
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,567
    Are you SURE this is a R-22 unit?

    The pressures your describing don't even CLOSE to jive with a 22 system.


    How do you reach the conclusion that, with a LOW suction pressure, your compressor is bad?

  3. #3
    Join Date
    Jul 2003
    Location
    Massachusetts
    Posts
    288
    solenoid?
    "ok, everyone just calm down."

  4. #4
    Join Date
    Oct 2011
    Location
    midwest
    Posts
    58
    name plate says r 22.. I didnt reach conluction yet... I would like to hear you guys on this one.. its strange that when i charged this unit and got full sight glass my high side was only 120 psi and my low was 20... Low pressures would indicate ristriction somwhere? I got low amps on one of the wires from compressor what would that indicate?

    I did check my solenoid. It opens and closes fine.

  5. #5
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,567

  6. #6
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,595
    Stupid question....but are the backs of the evaporators clean/not froze up?

  7. #7
    Join Date
    Oct 2011
    Location
    midwest
    Posts
    58
    jp, I didnt check superheat.

    Evap looks okay. Good air flow.. SO does condensor... I just dont get it why my head pressure is so low.. When i was there i felt the reciver. IT was hot but condersor was not.

  8. #8
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,595
    Quote Originally Posted by otto8 View Post
    jp, I didnt check superheat.

    Evap looks okay. Good air flow.. SO does condensor... I just dont get it why my head pressure is so low.. When i was there i felt the reciver. IT was hot but condersor was not.
    Headmaster?

  9. #9
    Join Date
    Jan 2010
    Location
    Toronto,Ontario Canada
    Posts
    355
    as a tech i got taught that putting on gauges is usually the last thing to do when at a service call. if you are at a call check the easy stuff. everything visual condenser/evap fan blowing feel the lines frost lines funny smells oil spots funny noises
    check stat and check power into unit.
    to check if system is low put your amp probe on the common terminal of your compressor and see how the amps are like does it match the rated amps if not let your boss know or decide what to do from there. reclaim it all? find leak? maybe too much refrigerant. then start understanding if there is voltage at places line/load control? safeties open? timeclock solinoid see if its in defrost.
    you can usually diagnose the system without putting your gauges on and when it is finally stars running then put your gauges on to see if the temps/pressures match what you want them to be. always do your visual and electrical tests first. it will make you a better tech (-: and i started to do this too. do your superheat and sub cooling on the units are soo important! it makes you more aware of things how they actually work. then when your boss asks you whats up u can tell him stuff usually bosses already know whats up by u telling him stuff like that and he can direct you to the problem

  10. #10
    Join Date
    Apr 2007
    Location
    Scottsdale,AZ
    Posts
    80
    I would agree with not putting gauges on right away if it were a i/m. If that is a 3 phase I would want to know why leg 3 is 5 amps. I would torch the receiver and see your level. Is your headmaster bypassing?

  11. #11
    Join Date
    May 2011
    Location
    Chas.,WV
    Posts
    30
    was there a rodent like smell ?

  12. #12
    Join Date
    Oct 2011
    Location
    midwest
    Posts
    58
    Very good point akelesis. I have been practising those techniques you just listed.This is giving me little bit more trouble than I expected...I dont think I looked into elecrtical problem... Thats what I overlooked.. bad habit. I was more focused on my high side being low when my sight glass is full... I just got more learning to do its seems like

    mizzterclean I will check that one when I get back to it... torch reciver and see your level?? Nobody told me that technique.. I would appriciate it if you can expalin it in more details.. Ben, there was no rodent smell... THANKS FOR YOUR HELP GUYS SO FAR

  13. #13
    Join Date
    Apr 2007
    Location
    Scottsdale,AZ
    Posts
    80
    Take your torch and run it up and down the receiver and then run your hand from bottom up until you find hot spot. Hot will indicate liquid level.in receiver. May take a few tries at first. A good diagnosis tool.to learn. Nothing wrong with hooking gauges if a unit is down. Good way to verify a failed.pressure control without guessing.

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