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  1. #1
    Join Date
    May 2012
    Location
    Calgary Alberta Canada
    Posts
    7

    Lightbulb Ductless Split-Low suction psi

    Hey everyone

    I was on a service call this morning for a ductless split system. The complaint was "not enough cooling" first thing i did was take a discharge air temp reading of 35F..i was expecting to see 55F. so i cleaned out the one filter i could reach, the rest of the unit is behind a massive flat screen. i put in the cleaned filter and cheked my pressures, gauges read 55psi suction..the remote was set to 71F and the compressor would shut off well before temp is reached and my pressure would drop to 50...with the tv infront of the unit i wasnt able to look much further into the call and told them i will be back once the tv is moved...My question is would the tv be causing a return air flow issue and adding heat to the room temp causing the low supply temp? any help would be great Thanks..

  2. #2
    Join Date
    Jul 2012
    Location
    Southwest
    Posts
    114
    My feeling is your charge, or is the unit re-circulating its own air, 55F return. The charge is critical on a DMS. I weigh it in exact. Read the manual, and do the math on length and ounces per foot. I find them way overcharged.
    I am saying its recirculating its supply air to the return, or its undercharged.
    They have a freeze protection sensor on the coil most of the time.

  3. #3
    Join Date
    Nov 2006
    Location
    Athens, Ohio
    Posts
    1,371
    The temperature sensor is mounted on the indoor coil. I suspect the TV is deflecting discharge air back into the return causing the short cycling.
    Ditto for the comment on the charge. I don't adjust charge on ductless systems by pressures. It has to be weighed in.

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