R22 is phasing out due to Montreal Protocol.

some info below for your reading:
https://www.hptcj.or.jp/Portals/0/ahpnw/3rd...nt%20presen.pdf

Is there any advertisement of R32 refrigerant in M'sia?

price should be significantly higher tho.

depends on horsepower.
1 HP usually can allow to 10 to 12m run.. indoor to outdoor unit.
Just verify from the technical catalogue or get more info from technical sales person.

higher HP can be slightly longer..
but mind you, there is a de-rating factor also.
Of course try to keep it short as much as u can

I will say R32 will be more energy efficient. However i have not much idea on the pricing.
Would be great if someone can gather and tabulate the pricing for comparison.
In term of energy consumption, should be able to see from online catalogues.

U guys need to know how inverters work.
Inverter is only good for part load conditions as the technology is able to let the compressor to run at slower speed to save energy.
But how the compressor knows when to run at slower speed? It is based on ur thermostat setting.
If u set room temp at 25 deg C, while the room is 24 deg C, it will run at part load. Also means it will only run at part load when the room is cold enough.

Imagine another case, u have a big room /space with substantiate heat gain, but u provide an undersized aircon which is 1hp.. if u do an experiment by recording the kWh on ur elec meter every 30mins interval, day 1 u run the 1hp aircon with no inverter and day 2 u run the one with inverter.
If like i mention, the aircon is undersize, both should be running at full and thus energy consumption should be the same.. therefore u dont see the saving.

why not?
simple google search also average lifespan of split wall mount unit can last about 12 years.
My parents house also have unit more 18 years.

i thought he is quite clear that the fan / blower / indoor unit is working fine but just that there is no cooling.
So it is the problem with the outdoor unit / electronic board / controllers, etc. etc.

I only want to mind you, sometimes when contractor isnt good at something but if they need to fix the problem, they will just simply ask u to change the whole thing.
If i were u, i will just try to get more quotation from contractors if possible.
Sometimes some very specific component faults, they might just get back to the supplier. When the supplier give the price, i guess that should be quite final.. not much to bargain anymore.

http://www.daikin.com.my/heat-calculator/
try that out..
I would recommend 9,500 to 12,500 btu/hr.

Note the disclaimer in the webpage.
Because it is really depends on the usage and heat gain from the room.
for example, what big is the window, window material, any roof heat gain, any insulation installed, how many heat generating equipment in the room, etc. etc.

that's why i highlighted the disclaimer and explained the basis of aircon sizing or design.

6000 btu/hr is quite on the low side but not that i am saying it cant achieve the required cooling.
But i guess there are chances that your AC is unable to cool down on certain hot day time.
Usually night time won't be an issue.

good point, that's where inverter come in.

but still depends on one budget on what to choose.

u never heard what is "window unit"?

probably refrigerant leak.
So have to check for leakage and top up gas.