I've a LG 1.5 tonne split AC in my room. As with many LG models, the ac comes with auto shut down feature of the outside unit as soon as the room temperature reaches the temp set in the AC. So this leaves me with two scenarios and I need help in determining which is ideal for less power consumption.

Scenario 1:

I set the temp in AC to 28-29 deg cel. In doing so, the outdoor unit runs for about 12-15 minutes and then shuts down for around 5 minutes (until the room temperature rises again and the cycle continues)

Scenario 2:

I set the temp in AC to 23-26 deg cel. The outdoor unit, in this case, runs for around 35-50 minutes and stays off for around 5-10 minutes and the cycle continues

I've come across suggestions that the outdoor unit consumes a tremendous amount of power to start and hence it's recommended that the unit stay on for longer duration as opposed to frequent on-off in order for less power consumption, but I'm not sure how genuine this information is.

Any inputs?

If it helps in any way, the region in question is India.


Model Name: LSA5VP3M

  • 1
    Often overstated, not sure in this specific case - yes, there is a starting "surge" no, it can't actually be all that much power or the wires would melt. This is an advantage of variable speed units that reduce speed to match load, but given you have what you have, any power savings will mostly be from where you set the thermostat (i.e. how much you cool.)
    – Ecnerwal
    Apr 19, 2020 at 14:01
  • Can you get us a model number for the A/C? Also, is this a window-type unit, or a mini-split? Apr 19, 2020 at 14:03
  • Question says split, mentions "outside unit" so probably not a window unit
    – Ecnerwal
    Apr 19, 2020 at 14:12
  • @ThreePhaseEel Updated answer with model name and link
    – asprin
    Apr 19, 2020 at 14:43
  • @Ecnerwal So if I'm understanding this correctly, you're saying scenario#1 is more power saving than scenario#2? And by power saving, I mean lower power bill
    – asprin
    Apr 19, 2020 at 14:44

2 Answers 2


In a nut shell, the cooler your home, the more your electric bill will be. You pay for your unit to run, not to start up. Sure, there is an increase in current when the unit starts up but the increase only lasts for a few seconds and there is a slight voltage drop when this occurs. It will have a very negligible affect on you bill. Scenario 1 would be your best option.

  • Yes, the percentage of time that the AC runs should be higher if the temperature set point is lower. This will override any startup power. The OP has large ranges so the evidence is inconclusive. But, if I pick some values that fit the data: Scenario 1: On 12, Off 5 = 70%. Scenario 2: On 40, Off 10 = 80%.
    – Mattman944
    Apr 19, 2020 at 15:48

The start cycle is apparently a strain on the compressor. In 25 years I have had 2 units replaced : after replacing the start capacitors and start relays a few times. Ideally you want a thermostat that you can adjust the on/off range to give longer cycles - fewer starts. I just had the 3rd new unit put in and the installer put in a thermostat with a longer range. I have not gotten an exact range because the new unit is so quiet that I don't often notice the start/stops. Power use wil be primarily depend on the total time it is on, regardless of start/stops.

  • This isn't necessarily true of more modern units. My new one has an "adjustment" and "maintenance" mode (which uses slightly less). Your mileage may vary, especially on mini-splits.
    – Machavity
    Apr 20, 2020 at 15:50

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.