In that case the compressor is a fixed speed unit...and raising the airflow on indoor unit will simply cause faster heat loss..thats all.
When buying inverter AC go for tropical model which is listed for full capacity at T3 = 55C.
Because air conditioners are actually heat pumping device, they move heat from a closed space to open space where it does not matter...and their capacity is relational to their working ambient...a unit rated for 18000 BTU at typical T1 = 35C will lose a lot of capacity as outdoor temperature rises and the whole unit may fail to cool when temps hit certain high...Also humidity has a bad impact on AC performance because water vapour condensing and draining from the indoor unit is robbing energy from the unit...hence why the drain water is so cold..
You can upgrade your existing AC to inverter unit.. it is a simple swap with some cutting and welding..may save you upto 50% cost over replacing the entire unit...but since R22 is being phased out the unit can be charged with R407.
Inverter simply means it has a permanent magnet BLDC motor. You can go the easy route of simply swapping a fixed speed BLDC compressor in..which should save you around 40% in energy plus reduced starting load....or go high tech and get complete power electronics for a variable speed compressor.
The compressors are sold as a kit which includes power board, control electronics and indoor remote.
