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  1. #1
    Join Date
    Apr 2006
    Posts
    109

    Walk-in cooler from kolpak

    Got a call,walk-in warm..found comp. cycling off low press. switch. hook on my manifold. system is r22 press, actual 145psig and 15 psig on suction line. system leak I thought. started to add refrigerant. pressures wouuld not come up.so pulled out all refrigerant,nitrogen press test,no leaks, pulled 500 microns and add R-22,still cant get suction or head press.(had lo press. switch jumped) press. do not equalize when i turn off comp. liquid line solenoid energized and calling. thinking bad comp, as it will not hold a pumpdown.cooler is at 75 deg. so txv valve should be open and press. should equalize during off cycle,right? now i am not sure if i should change comp. Am I missing something???
    Never Assume Anything

  2. #2
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,736
    Quote Originally Posted by freeeze43 View Post



    cooler is at 75 deg. so txv valve should be open and press. should equalize during off cycle,right? now i am not sure if i should change comp. Am I missing something???

    sounds like restriction or bad txv.

    if unit is pulling down and shutting off at lp switch the compressor would be my last choice.........

  3. #3
    Join Date
    Feb 2006
    Location
    In the house normally
    Posts
    219
    I second that emotion.
    What we have here, is a failure to communicate........

  4. #4
    liquid line solenoid energized and calling

    Does not mean its opening!

    Close the king valve, run comp a minute, with LLS calling, the loosen bolts on LLS and do a "deminimus" release, remove piston, close LLS back up, open king valve and try again.

    Also, if powerhead on TXV is bad, it will become a closed LLS. Just FYI
    Last edited by Leo3006; 09-26-2008 at 08:36 PM.

  5. #5
    Join Date
    Apr 2006
    Posts
    109
    forgot to mention that sightglass had no refrigerant passing thru, filter drier was just replaced a few moths ago, could this get fully restricted. also i always thought that if you had a restriction on liquid line, that head press. would be higher than normal,not lower... still learnin thanks...
    Never Assume Anything

  6. #6
    Join Date
    Apr 2006
    Posts
    109
    Close the king valve, run comp a minute, with LLS calling, the loosen bolts on LLS and do a "deminimus" release, remove piston, close LLS back up, open king valve and try again.

    Also, if powerhead on TXV is bad, it will become a closed LLS. Just FYI


    good tip. thanxs
    Never Assume Anything

  7. #7
    Join Date
    Sep 2008
    Location
    Cedar Rapids, IA
    Posts
    486
    Does the TXV have a strainer? I've seen them get plugged solid. I agree that something on the liquid line is plugged. If you have any schraders check your pressures. The fact that you are not pumping down into a vacuum indicates that some refrigerant is flowing, just not enough. Check the drier, LLSV, and TXV for the temperature of the line into and out of. If the out of is colder than it is suspect. Even though you said you are not seeing flow in the sight glass if it was empty except for 15psi I would expect to see the drier or the LLSV getting cold if they were the culprit, so I am thinking it is the TXV.

    Try turning its adjustment wide open. This will sometimes let debris blow through. (or put its bulb in hot water.) Then adjust it back to proper superheat.

    I once had a liquid line that was frosting at an elbow. Took it apart and found a rubber plug that was originally used to seal a length of copper pipe. Someone forgot to remove it an amazingly the system worked for several years w the plug cocked in the larger sized elbow. If finally plugged it too much and caused a down system.

  8. #8
    Join Date
    Apr 2006
    Posts
    109
    So from what I am hearing is that if you have a high side resriction ,the head pressure will be low on a full charge.
    Never Assume Anything

  9. #9
    Join Date
    Jun 2008
    Posts
    73
    How is the sight glass installed? Face up? should be on an angle. You can be getting a false reading if upright. Does the drier feel like it has a temp change across it? Solenoid sound good? I take it because its a pump down that you have a reciever. Head will go down on pumpdown if the reciever is sized correctly.
    I agree on a restriction in the liquid line.

  10. #10
    Join Date
    Apr 2006
    Posts
    109
    checked out system again, got no refrigerant downn at lls, it seems to stop at receiver. did anybody here of pickup tube in receiver plugged??? if so how to check..
    Never Assume Anything

  11. #11
    Join Date
    Sep 2008
    Location
    Southwestern Ontario
    Posts
    99
    Could the receiver be logged with oil.

  12. #12
    Join Date
    Sep 2008
    Location
    Cedar Rapids, IA
    Posts
    486
    Quote Originally Posted by freeeze43 View Post
    So from what I am hearing is that if you have a high side resriction ,the head pressure will be low on a full charge.
    True only if the restriction is after the condenser in the liquid line.

  13. #13
    Join Date
    Sep 2008
    Location
    Cedar Rapids, IA
    Posts
    486
    Quote Originally Posted by freeeze43 View Post
    checked out system again, got no refrigerant downn at lls, it seems to stop at receiver. did anybody here of pickup tube in receiver plugged??? if so how to check..
    Is there a headmaster control valve? This valve has 3 pipes, one to the hot gas discharge, one from the liquid line out of the condenser, and one going to the receiver. If head pressure is below its rating it will not let liquid past. W R22 and 145psi it will be closed trying to flood the condenser. But because you do not have enough gas to flood the condenser you will get the results you are seeing. Your charge is too low. Add gas until head pressure goes over 180# then you should see liquid if the valve is working correctly. Add enough gas by weight to flood the condenser beyond the point that you start getting liquid otherwise the problem will re-occur when it gets colder.

    You should be able to test this scenario by blocking the condenser w cardboard until the head pressure climbs above 180

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