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Storm season

Will a generator run your air conditioning?

The running load is modest. The starting surge is not. Pick your system size and whether it has a soft starter to see the figures people plan around — then let an electrician size the generator properly.

Your system

The capacity digits are on the data plate of the outdoor unit.
A soft starter reduces the current the compressor draws at start-up.

Typical figures only. Your unit's nameplate (RLA and LRA) and the generator's surge rating decide the real answer, and an electrician makes the connection safely with a transfer switch.

What to plan around

Running load
3,600 W
Start-up surge
14,400 W
Generator people usually look at
14 kW or more

Without a soft starter the surge is the deciding number, and it is several times the running load.

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What actually matters

Four things before you buy a generator

  • Read the nameplateRLA is the running current, LRA the locked-rotor current at start. Those two numbers beat any rule of thumb.
  • Consider a soft starterFitted to the outdoor unit, it cuts the start-up surge substantially and can bring a smaller generator into play.
  • Whole system, not just the compressorThe indoor blower, the furnace controls and any heat strips draw power too.
  • An electrician connects itA transfer switch keeps power out of the utility lines. That work is theirs, not ours — we prepare the HVAC side.

After the power comes back

Give the system a few minutes before restarting it, so the pressures equalise. If the outdoor unit was under water, leave it off and call — water in the contactor and compressor terminals is not something to test by switching on.

We check the electrical side, the capacitor and the contactor after a long outage, because that is where surge damage usually shows up first.

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A technician checking the electrical disconnect beside an outdoor unit
(281) 270-7704