Air Conditioner compresor intermitently shuts down?

[pkspeaker]

I have 2 mitsubishi mr. slims in my condo. they have 2 led lights labeled 'operation' .. when you turn the thermostat down to say 24* both operation lights come on and they go into full power mode with the outside compressor running. The compressor of the one in the sitting room has started to intermittently shutdown when its set to full cooling mode.. but the compressor works it's just becoming intermittent when its not supposed to..

just checking if anyone knows what this is before i call maintenance and get the run around..

[phetphet]

Could be anything. Probably short of gas. The only thing you could probably do yourself is clean the condenser anyway, so best call an engineer in to have a look.

[Pib]

When the room reaches the set temp like 24C, the compressor is suppose to cut off for a fixed speed A/C. By fixed speed A/C in mean the original/standard type where the compressor (outside unit) is suppose to cut off when the cooled area reaches the set temp...the inside unit will continue to run though...once the temp rises a degree or so above the set temp the compressor will cut back on. That's the way a fixed speed A/C works.

Now if you have an invertor A/C, normally the compressor will just slow down once it reaches the set temp but they can also cut off for short period depending on the environment (i.e., like cooler weather) and they just don't need to even run at slow speed...the invertor electronics decide I can save even more power by just turning off for X-minutes and still maintain the set temp.

Maybe your setting room room is just being cooled to the set temp of 24C and the A/C is compressor is turning off as it should if a fixed speed A/C. And maybe the A/C for your other area, maybe a larger area, is having to work harder to maintain/reach the set temp which means it won't turn off or turn off much less.

It is beginning to cool off in Thailand, A/Cs are not having to work as hard to maintain room temperature, therefore A/Cs compressor will not be working as hard/spending more time in off mode which will also lower your electric bill.

If your 24C temperature setting is still being met, then you probably don't have anything to worry about...the A/C is operating normally. But if the A/C can't cool down to the 24C and the compressor is turning off then its got a problem.

Edited October 1, 2015 by Pib

[IMHO]

Yep, sounds like normal compressor cycling to me. The less cooling work they need to do, the more often the compressor is off.

Even inverter AC's can cycle the compressor on/off.

[aliep]

On a Mitsu the first light means it's swtiched on, the second light illuminates if the incoming air is more than 2 degrees away from the set point. If it's cycling with both lights illuminated, you have a problem.

[Pib]

Different number of lights on different models. I know the OP is talking a Mitsubishi A/C but if like my York A/Cs throughout my house...7 of them in the same York model family...depending on their BTU size they have a different number of lights on them and ranging from 1 light to 4 lights. And the lights' on or off status mean different things. None of the lights turn off when the compressor is off...none of my York A/C lights indicate if the compressor is running or not. Maybe at least some of the Mitsubishi models are the same way. Read the manual for your model to see what the lights mean....every model will be different.

[jacko45k]

Sounds like you have a self resetting thermal overload (bi-metal) in the motor.

A service of the unit may improve the motor cooling, or the overload itself may be defective.

The motor may be overloaded too.

This protection is for overheating windings or high current and reset after 10 minutes or more.

I don't think the overload is accessible in the compressor and likely require a motor change.

[pkspeaker]

ok tx for the replies, must be the compressor motor getting old or overheating, its not that the room temp is going below 24* because it will quit even at 22.. and the room temp is about 27-28 when it quits, it quits even when the other one is off and the other one is functioning normally

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[fred Kubasa]

Re read Pib's comment. I have Mitsus and what you describe is the way they aare supposed to work !