Ive been reading alot about air conditioners that run on short cycles, meaning they shut off and on too often.

I just cant find anywhere, that tells what a normal cycle should be.

I just bought a Mitsubishi 18k btu unit for a 25 sq mt livingroom.

It runs for about 20 minutes and shuts off for about 5 min.

Its set at 30, sun never touches the walls, steady drip out the drain pipe. It does a good job of cooling the room.

Is this a short cycle or normal?

Perhaps it's the thermostat causing it to cut out once it reaches a desire temperature. Try turning the t'stat to a colder temp to see if it runs longer.

Short cycling on /off, from what I have seen is normally a lot quicker and can signify that the refrigerant needs recharging, or the condenser needs cleaning.

It shouldnt need refridgerant or cleaning, its brand new.

Ill try turning it down.

Any idea what a normal cycle is?

That sounds pretty normal for a non-inverter with such a high temp, therefore low delta.

My A/C is 9K BTU Mitsubishi with a 20 m2 well insulated room and it cycles off/on maybe 15 min after reaching 25C. Something like that.

Edit: Well, now that I sit here listening to it... maybe more like 5 min cycle. Pretty sure it lengthens into the night, though.

I agree that 25 min running vs. 5 min pause at such high temp setting is not what I would expect.

Ours is quiet for much longer than 5 min in half an hour,

18 k BTU for 25 sqm?

Sound like just about enoigh.

From the web: it seems to be better to have a smaller AC running like this (25 / 5) vs. an oversized one?

Wait for the electricity bill an let us know the outcome

It sounds to me as if it is oversized for the room, if so then not much you can do now.

Which model do you have?

If it is like mine it probably has a "Dry" mode which will cool a bit. I would give that mode a try and see if it is good for you.

Thanks for the replys.

Its a mr slim.

Just got the elec. bill. Went from 400 a month to 800, not bad.

I tried turning it from 30 to 28 degrees and put the fan on auto . The cycle time is much longer now and it works great.

We'll see what happens.

Thanks for the replys.

Its a mr slim.

Mr Slim covers a fairly large number of models. It includes regular, wide and long, inverter, ceiling cassette, single phase and 3 phase units

So that isn't the model.

FWIW we just got a MS-GK09VA+MU-GK09VA for a 16sq meter room which is a 9000 BTU unit and it is easily enough. So based on that I would have gone for a 13,000BTU for for a 25sq m room.