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TXV malfunction
A/C was short cycling: 3-4sec on and off 3-4minutes early this week hot summer, over 90’s. Normal at night, esp if turn off 2 out of 3 zones.
A Tech came out 3 days ago: no freezing any line, clean filter, washed fin, drain open, not compressor, all gauze reading good except one: around “2.3-3.0 instead of around 10”. He has never seen this and called a supervisor who said, need a New TXV! Next day quote $970 + tax. No more problem yesterday and today with outside temp 80’s. Would appreciate your advise. -
6 Replies
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I’d have to know more about the system. Capacity, and type of refrigerant control (TXV) Electronic or mechanical. Type of refrigerant.
Age of the system would be nice as well.
Rarely does a Mechanical TXV fail. However, the charge on the tops of the valve sometimes corrode through and lose their charge. A $40 valve charge and a hour of labor is a long way from $900.
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Trane 4 ton 4TTB3-D outside unit, short cycling again in the morning 2 days ago and run normally after several short cycled.
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Fan coil unit First Co. model 48HBXB-HW, R-410A. Outside unit Trane 4TTB3-D, 4 ton,
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TXV is mechanical.
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Sporland, Danfoss, or Alco valve?
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You may have a drop of moisture in the system. Turns to Ice at the TXV and blocks it temporally. The short cycle concerns me, because on AC units the only interrupter is the high limit. Usually a cooling fan problem. But if it is 3 phase, check for a phase monitor or a delay start relay. Sometimes used to stage start load due to power outage.
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