Hi, we had our air cons cleaned and that was all good but it is so noisy. Not the motor or compressor but it is like the plastic case(?) cover/shell makes cracking noises.. all night. It did it before but worst now.

Also for some reason this air con goes on and high and low, high and low..constantly. We have tried every setting but it never just stays at one noise level (compressor) It's a 6 year old mitsubishi.

Thank you

Is the cover securely closed?

If not that could explain the rattles, and the cycling - as cold outlet air could be leaking directly onto the temperature sensor..

You could call them back to check but suspect it may be cooling better and the change is making the plastic case make noise (had real issue with old LG unit). Try running high fan speed to make cover noise/mask noise - even if you have to adjust air flow or turn temp to warmer setting. Fan should stay on setting unless using "auto" or a special night/humidification type program. Make sure it is set for cooling only.

The cracking noise is the cooling effect (the freon tubing/plastic structure expanding and contracting ever so slightly)...not uncommon to hear a little bit of that occasionally, especially shortly after the outside unit/compressor kicks on which creates higher freon pressure/starts the cooling process in the whole system. Many times ensuring the plastic case is secured tightly to the wall, filter door closed securely, or just wiggling the whole inside unit on the wall (which may help secure it down a little) can make a big reduction in the sound. This cracking noise can vary greatly from brand to brand, condition of the unit, how well the unit is secured to the wall/floor, etc.

Thank you will have a look, appreciate the feedback.