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  1. #1
    danny x Guest
    Traulsen Model G20010 R22 System 23 oz

    Unit was running at 0# backside pressure. The Cap tube was frozen back six inches from where in enters the evaporator. I figured it might be low on refrigerant. I replaced the existing line drier with one having an access, pulled a vacuum and attempted to recharge to 23 oz. Before reaching the proper weighed in charge my head pressure was above 300# (ambient temp in the kitchen was 95)

    Possible the ice is a sign the cap tube is restricted where it enters the evaporator? I have normally found the restriction at the drier.

  2. #2
    Join Date
    Jul 2005
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    28

    Smile

    Danny
    It looks like the cap tube is blocked if frosting so far back did you check it for restriction when you changed drier? if no restriction when checked could be moisture,you may be able to cut back cap tube or it will require replacing.
    Regards
    Frosty-ne

  3. #3
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,570
    replace the cap tube. Better yet put a AAA port txv in it.
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  4. #4
    Join Date
    May 2004
    Posts
    11,963
    Originally posted by Freezeking2000
    replace the cap tube. Better yet put a AAA port txv in it.
    and use an oversized liquid drier and stand it straight up. It will act like a small receiver.

    dont try this at home folks, professionals only

    but he should get away with pulling the cap tube from the evap and cutting it back a few inches and replace it along with a new drier.


  5. #5
    Join Date
    Jul 2000
    Location
    Guayaquil EC
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    10,260
    Originally posted by danny x
    Traulsen Model G20010 R22 System 23 oz

    Unit was running at 0# backside pressure. The Cap tube was frozen back six inches from where in enters the evaporator. I figured it might be low on refrigerant. I replaced the existing line drier with one having an access, pulled a vacuum and attempted to recharge to 23 oz. Before reaching the proper weighed in charge my head pressure was above 300# (ambient temp in the kitchen was 95)

    Possible the ice is a sign the cap tube is restricted where it enters the evaporator? I have normally found the restriction at the drier.
    If you had seen the ice at the outlet of the drier it would have been obvious that the drier was restricted. In this case however, the icing at the end of the cap tube tells me that the system is either low on charge or the cap is plugged near the end.

    The answer to that would lie in the amount of liquid subcooling you have before the cap tube. High LSC = Restricted, Low LSC = Low Charge. Easy to do and no surgery required.

    From what you say about the head pressure going to 300# during charging I would say there's no restriction in the cap at all because it's feeding the refrigerant like it's supposed to and resulting in a high compressor load. If there was a plugged capillary tube, you'd get low suction and low discharge pressure.

  6. #6
    danny x Guest
    Thanks for the replies guys

    Icemeister,

    If my cap tube is restricted you’re saying I would have a low discharge pressure? Why would it be low and not high due to a restriction? Wouldn’t the discharge of the compressor try to pump against the restriction? Would you mind elaborating?



  7. #7
    Join Date
    May 2004
    Posts
    11,963
    allow me..

    Danny

    where is the compressor going to get the fresh refrigerant to keep up the discharge pressure? See?

    Low suction = low discharge and refrigerant storage in condenser coil.


  8. #8
    danny x Guest
    I had a feeling that was the answer

    One other question though, why wouldn't the compressor pull down into a vacuum while trying to over come the restriction? For example, if a liquid line solenoid is close, the compressor will pump down.

    Thanks again guys

  9. #9
    Join Date
    May 2004
    Posts
    11,963
    it is rare to have a 100% restriction in a cap tube.

    Also... did you see a low pressure control on the system you are working on? No? So how do you know it doesn't pull a vacuum when you ain't look'n?


  10. #10
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,260

    danny x.........

    Lusker & I went to the same school, me thinks.

  11. #11
    Join Date
    May 2004
    Posts
    11,963

    Re: danny x.........

    Originally posted by icemeister
    Lusker & I went to the same school, me thinks.
    The meister graduated... I just became a sacrificial victim on the subject.



  12. #12
    Restriction will produce elevated head pressure.

    Blockage will produce zero pressure on low and reduced pressur on the hi side.


    Unless a fractional horse sealed system is suffering from burn outs and havent been properly cleaned up ...flushed out .... made spotless inside .... you NEVER EVER want to replace a OEM drier with one which is extremely oversized!!!

    Unless of course, you want a mini receiver in your system now

  13. #13
    Join Date
    May 2004
    Posts
    11,963
    Originally posted by R12rules
    Restriction will produce elevated head pressure.

    Blockage will produce zero pressure on low and reduced pressur on the hi side.


    Unless a fractional horse sealed system is suffering from burn outs and havent been properly cleaned up ...flushed out .... made spotless inside .... you NEVER EVER want to replace a OEM drier with one which is extremely oversized!!!

    Unless of course, you want a mini receiver in your system now
    Dr Freeeeezeking was talking about slaming a AAA port in the suck'r.. how ya going to feed it? Ya make room for more !

    The only restriction that produced an elevated head pressure was my own after I hit it on the shelf just above. OUCH.

    Bob.. you are spoiling all my fun.

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