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  1. #1
    Join Date
    Sep 2010
    Location
    miami,fl.
    Posts
    605

    restriction or low charge

    york 3 ton split system straight cool. 1 tech was at the house earlier in the day said he added gas and low side wont come up above 45ish. with high superheat sounded like low charge or restriction. i stop by on the way home its night time. i didnt want to waste much time i pumped down the unit checked orifice ( no txv) clean inlet screen is clean. i blew liquid line and suction line with nitro since i had it open. pulled vacuum. started the unit back up. same thing. pressures were 45/150. i tried adding gas seems like the low side valve core was messed up. it was taking the charge real slow. got the pressures up to 60 low side 170 hi psig.
    liquid line temp was 73 degrees out door temp 73 degrees,i see inside the condenser there is a copper filter dryer. based on subcooling and liquid line temp im leaning towards a restriction. the only place left it could be is in the high side king valve or filter dryer in the condenser. or the system has a leak im planning on recovering the charge. removing dryer install new outside condenser and gas her back up. hopefully blow through the dryer and find it to be clogged. any input by the way its an r22 system. if more info needed ask me if i have the answers ill input thanks

  2. #2
    Join Date
    Sep 2011
    Posts
    85
    whats the subcooling? whats the temp. diff across the filter drier? whats the temp. diff. across the king valve? if you think there is a restriction there, i would check for refrigeration effect.

    another trick i've learned from a guy, was to run the condenser, but disconnect the fan control. watch the distribution tubes (in the evaporator) and make sure they all ice up evenly. if one doesn't ice up (or ices up slowly), it's not getting refrigerant.

  3. #3
    Join Date
    Jul 2011
    Posts
    117
    Quote Originally Posted by wdshea View Post
    whats the subcooling? whats the temp. diff across the filter drier? whats the temp. diff. across the king valve? if you think there is a restriction there, i would check for refrigeration effect.

    another trick i've learned from a guy, was to run the condenser, but disconnect the fan control. watch the distribution tubes (in the evaporator) and make sure they all ice up evenly. if one doesn't ice up (or ices up slowly), it's not getting refrigerant.

    only do that with a txv...

  4. #4
    Join Date
    Apr 2012
    Location
    winnipeg
    Posts
    1,330
    oh my....
    it was working.... played with it.... now its broke.... whats the going hourly rate for HVAC repair

  5. #5
    Join Date
    Oct 2011
    Location
    Chicagoland Area
    Posts
    4,509
    Quote Originally Posted by carmon View Post
    oh my....
    Lions and tigers and bears....
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    I know enough to know, I don't know enough
    Liberalism-Ideas so good they mandate them

  6. #6
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    1,974
    When you pull the charge, weigh it and check it against the suggested amount. I'd also stabalize the tank temp and check the pressure against the chart for refrigerant specified.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  7. #7
    Join Date
    Jan 2013
    Location
    Central, FL
    Posts
    29
    A restriction anywhere in the liquid line will show a temperature drop if there is any liquid in the system. That will be the clue you need.

  8. #8
    Join Date
    Jan 2007
    Location
    Mn the state where absolutey nothing is allowed
    Posts
    1,332
    you know 1/2 the ac is inside the house. why are you looking outside


    not saying, just sayin
    my boss thinks its possible to repeal the laws of physics

  9. #9
    Join Date
    Feb 2010
    Location
    In a boiler room
    Posts
    7,046
    Quote Originally Posted by Ductfisher View Post
    A restriction anywhere in the liquid line will show a temperature drop if there is any liquid in the system. That will be the clue you need.
    Not if the subcooling is high before the restriction. It is possible to have a significant pressure drop across a restriction but have no temp drop.

    Anthony, I think you are on the right track with the restriction. I would bet on that copper drier in the unit.

  10. #10
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,607
    what does the filter and indoor coil look like .
    We really need change now

  11. #11
    Join Date
    Jan 2013
    Location
    Central, FL
    Posts
    29
    I stand corrected. After rerreading this thread I say it is under charged. What is the TD across the coil?

  12. #12
    Join Date
    Sep 2010
    Location
    miami,fl.
    Posts
    605
    well i went to the house today saturday customer wasnt home so i weighed my tank empty recovered gas removed the liquid dryer from inside the condenser, dryer was slightly restrictive i dont think was the root cause but glad i removed it. i recovered 9lbs and compared to the factory charge on cond. nameplate, said 9lbs 1 oz. the end result it has a leak beacause i had added about 3lbs when i went there thursday night. so that tells me originally it was low on charge. customer arrived home as i was cleaning up after dumping the gas back into the system. i went inside the house and the leak detector was going off in the finned area of the coil. and wouldnt stop turned detector off waited about 5 mins turned it back on once i went back to the same spot it went crazy i usually like to spot the leak to confirm but ima conclude its in the coil. i wanted to get back and say the out come i appreciate your input.

  13. #13
    Join Date
    Jul 2012
    Location
    Dillwyn, VA
    Posts
    43
    Leaky evap coils are famous these days

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