Are you getting little to no cold air? Do your air conditioner pipes have ice on them? There are two basic reasons why ice can form in this situation.
1. Little to no air flowing through the evaporator coil, or
2. Low refrigerant.
If you know the correct model replacement filter to buy you can try replacing the filter. Once the filter is replaced let the unit sit turned off until all the ice is gone. Then turn on the unit and check to see if ice has formed again after a few hours. If there's no ice, you just repaired your unit with out having to call for repair help. If your unit has iced up again, you will need to contact an air conditioner repair pro.