My RCAC takes a long time to heat or cool the room, is there something wrong? What should I do?

My RCAC takes a long time to heat or cool the room, is there something wrong? What should I do?

It is best to check the list below to evaluate if something is wrong:
Is the control setting correctly set to heating or cooling?
Does the unit switched on? Does it have lights on?
Is the temperature properly set?
Are air quantity and direction properly controlled?
Are air filters clean?
Are areas directly below or next to the air conditioner blocked by furniture or other objects?
Are windows and doors closed?
Has the ventilation fan stopped?
If you have checked all of these and there is still a problem, you should contact your supplier.