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Low ambient A/C maintainance?

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Alan_6
Alan_6 Member Posts: 87
in THE MAIN WALL
Is the a way to do a accurate check of refrigerant charge, in low ambient conditions on a residental split A/C system? Some people think you can by restricting the air flow across the condensor. I have had no luck with this method.

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  • clammy
    clammy Member Posts: 3,113
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    charging

    chk your sub cooling on your liquid line and also chk your super heat at your suction line near your condensing unit.Is this for a/c or refrigeration and what type of low ambeant control are you using a fan cycler or a fan speed controller there's a couple of varables.Also chk the manafactors spec they usally tell all restriction air across the condenser is a load of bs it's not the way to do it
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • Alan_6
    Alan_6 Member Posts: 87
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    I also think loading up the condensor is bs. I was just looking for opinions. The people that dispatch our calls send us out to check the charge on residential split systems. When it is as cold as 40 degree's outside. It never works, as a result, lots of call backs.
  • steve_26
    steve_26 Member Posts: 82
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    charging

    use a P/T chart.
    take your ambient reading add 30degrees and croos check your
    suction reading.
    not the best method but effective and very close until you get back some warm day...like that will happen.
    we have done some Nextel sites in the winter and have to charge the system it works.

    steve
  • steve_26
    steve_26 Member Posts: 82
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    loading

    By the way loading up the condenser is a very bad idea.
    liquid slugging will kill the compressor if it is loaded to much and it backs up in the condenser which diminishes it's ability to reject heat.

    steve
  • David_5
    David_5 Member Posts: 250
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    What we do

    is try to check residential a/c's starting in May. Even then some mornings can be around 40 degrees. We check the temperature difference on the indoor coil. If it is between 15-25 degrees then all is good. The reading is also recorded on the job order. This is not perfect but there are very few callbacks. I am not a fan of checking system pressures as part of maintenance. Servicemen loose the caps, the cap gaskets fall out, or just don't put them back on. Then you have a leak. Unless you have a charging chart by the manufacturer for that particular unit most people cannot get the charge right. JMHO

    David
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