My air-con is not as cold as before. I tried to lower the temperature, but when i try setting the temperature to 18 degrees, the remote just shows 18 degrees for like 5 seconds before going back to 31 degrees. Few months ago, i left the air con on for the whole night and when i offed it in the morning, it dropped some ice. Does this have anything to do with the aircon not being cold?

We set ours to about 70 degrees Fahrenheit or 18-20 Celsius. That is a fairly even temperature not to hot, not to cold. Hope this helps!

check that all the doors and windows are closed as ac units do not work well when trying to cool the world
is the ac unit too small for the room size
I suspect that because it is working the problem is outside the ac control
is the inside fan working and blowing out cold air

because you have the temperature set at 28 degrees celcuis . Change the temperature to 18 degrees and it will cool 28 is hotter
It is a reverse cycle air conditioner it will warm the room if you set temperature to 28 degrees . Set it lower and it will blow out cold air.
Have exact same air conditioner as I recognise the remote control.
point it at the air conditioner when altering the temperature setting.
Check under the slide compartment also on the remote for more advanced settings.

Hello... may be you can set the desired temperature and later the remote control and/or the internal unit show to you the temperature of the air ... just let the air conditioning try to match your desired temperature...
Watch this...
https://www.youtube.com/watch?v=2Ck_xsdrmSM

set your temperature to say 20 degrees celsius and the air con should automatic change to heat,

If the dial is in such a format in your refrigerator, try a setting at 3 if the range is 1-5, and at 4 if the range is 1-9. For the freezer, a setting at C is suitable.
The ideal temperature in the refrigerator ranges between 34 - 38 degrees F or 1 - 3 degrees C. So that foods such as vegetables and fruits remain fresh and crisp, the temperature may be set around 38 degrees F or 3 degrress C.
The ideal temperature in the freezer ranges around 0 degrees F (-18 degrees C) or lower. See more at:
http://www.buzzle.com/articles/refrigerator-temperature-settings.html

It is likely to be either the circulation fan in the freezer or the defrost element. The cold air is blown from the freezer into the fridge if the fan doesn't work then no cold in fridge.Otherwise it could be a defrost problem, if the element doesn't work the rear fills up with ice and the air cant flow. Both are behind the rear panel of the freezer

I understood from your statement that the sensor bulb is not in position. Check it should facing towards return air. And normally, if you set 20 degree, it will cut off at the end of 18 degree and cut in at the beginning of 22 degree.

Is this a central unit or a window unit. The central unit does 15*----18 * temperature difference from the air comming in the return air grill to the air going out the supply air grills...9*----to ----14* degree different, and the unit is low on freon,, 15*--18* and the charge of freon is perfect, 19-----22* difference, then the air flow is too low , due to either a dirty filter,, dirty squirell cage blower wheel, and last , but not least, the ac inside coil is plugging up!

go here: http://www.partlinx.com/haier.asp
andsearch for the part. You have to start with your state, and then gofrom there. For my area, the remote is 19.99, plus shipping and tax.Also, try eBay. You can find a lot of things there!