There are several reasons that an AC unit may not be cooling. The following list is not all-inclusive but covers some of the more common problems: 1) Dirty or clogged filter - We recommend checking filters once a month and replacing them every three months. If you have pets, you will need to check them more often as they will cause more dust and dirt to accumulate. 2) Blocked airflow - If the unit is not positioned in the right spot, or if there is too much furniture blocking it, this can impede the airflow and cause the AC unit to work harder than necessary. 3) Incorrect settings - Sometimes people mistakenly think that they need to turn