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  1. #1
    Join Date
    Apr 2012
    Location
    Princeton NJ
    Posts
    125

    how tell which breaker to AC unit?

    Hi, i have 2 3ton AC units, the breaker boxes just say "AC." and "AC". I'm having a generator installed/transfer panel and need to select a specific AC--is there a way to tell which breaker goes to which ac? I seem to recall that i shouldn't turn on the AC unit if the temp is under 60. Is this true? If i could (it is 40ish now) that would be easy, just turn it on for a few seconds and flip the breakers one by one.

    thanks

    Steve

  2. #2
    Join Date
    May 2009
    Location
    Savannah, Ga/H.H. Island, S.C.
    Posts
    1,277
    It won't hurt to turn it on for a few minutes. It's a double pole breaker. Somewhere probably in 25 - 40 amp range.

  3. #3
    Join Date
    Apr 2012
    Location
    Princeton NJ
    Posts
    125
    Well thanks. But what is the rule, if there is one, about turning on an air conditioner when it is cooler outside? Can't do it but only a few minutes? Under 60? 50? If one of my kids turned it on in below zero would they ruin it. Thanx Steve.

  4. #4
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    5,659
    No it wouldn't ruin it, the compressor sometimes has trouble starting in cold weather and the indoor coil will freeze up if the outdoor temp is low (below ~60-65*F during prolonged run times.

  5. #5
    Join Date
    May 2009
    Location
    Savannah, Ga/H.H. Island, S.C.
    Posts
    1,277
    I don't know of an actual temperature to tell you. It's all relative to load/temps. Refrigerant pressure is directly proportional to temperature.

    Low ambient temps cause low head pressure thus the metering device does not get fed properly and the result is a starved evaporator coil. A starved evaporator coil causes loss of capacity, high superheat, and possible evaporator freezing. The pressure may be so low that it cycles the low pressure control (if applicable).

    But will it hurt the system? Not if you just run the system for a bit. I would NOT suggest prolonged run times.

  6. #6
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    It will be fine for a couple minuts. Turn one on at TStat and have some one outside standing by the one that comes on with a cell phone. Then you turn one breaker off. Then number them AC1 and AC2. Too easy.

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