Do you close your door at night?
Think of your room as a giant un-bustable balloon. You AC system is trying to pump a certain amount of air into your room. When your room gets so much pressure in it the balloon can't pop but the air can no longer come in either. This problem is often remedied by having a gap at the bottom of your door but it has become common for builders to fill this gap with carpet or add wooden floors but forget to adjust the door to allow the air pressure to escape.
Another common problem is builder will not do proper air balancing. When duct work is designed it should allow a certain amount of air to enter your room. We call this CFM or Cubic Feet per Minute. Through mathematical calculation we can identify the amount of heating and cooling an individual room will require. We turn this information into air changes per hour or the amount of air required to completely change out all the air in your room X number of times in one hour. This is turned into CFM. If the duct work is not properly done you will receive too little CFM and your room cannot get cold.
You need to search for an HVAC company in your area to preform a load calculation on your home and find out what the air balance of each room should be then properly adjust your homes CFM.
If you're too "open" minded, your brains will fall out.
Artificial intelligence is no match for natural stupidity.