Make sure the AC unit does have a free space to blow out the air.
I read up on your AC unit and it seams like it doesnt have a condensation tank leaving u with something that could be similar to be u sitting there spraying water between the walls everytime the compressor is working.
And on top of that, if ther's overpreasure where the AC is blowing out. meaning that it has nowhere to escape most units shut down to prevent overheating, work allot worse or using the compressor unit allot less and for shorter time making your expensive AC nothing more then a time to time 1000 watts table fan.
I had the same problem in a space of about 250cm to the roof and 80*130cm of floor area and walls made of concreat. Started with a 6cm in diamater pipe going from the toilet just taking in air from another room with a high RPM 120mm computer fan, not ideal but better then nothing.
this wasn't enough while growing with a 600w hps and a digital ballast in the same room so i just bought a second hand AC unit for about whats similar to 180 in swe. Tried to vent it out through the pipe i had going from the toilet but it was too tight and the AC kept shutting off due to safety mechanism so i just put back the old computer fan pulling in air then i drilled a hole through the door to the room in the same pipe diameter as the AC pipe and now i'm venting it out into my apartment.
This solution is not very discreat but i keep my room under 28 celcius with the AC set on 22, it can go down to 18 but then it starts to flush water out on hot days. Hope i helped u more then just talking about my previous experience.
btw, added to this i got all my windows open all the time and the other room i'm pulling air from is my toilet which i got closed and its in the middle of the house so its pretty cool. just dont want u to think im venting the same air back in as the AC just blown out.
in 1 month though im gonna rebuild the entire vent system for about 500 but the current one i just told u about is at least working fine for keeping the temp down.