how tell which breaker to AC unit?

[central nj]

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

[Brent Ridley]

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.

[central nj]

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.

[jtrammel]

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.

[Brent Ridley]

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.

[Tommy knocker]

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.