All air conditioners have filters. On whole-house air conditioners, the filter is usually found near the part of the return duck that attaches to the air handler. On window air conditioners the filter is located under the inside intake grill.
A few signs indicate that it is time to change your air conditioner’s filter.
Increase in your electricity bill.
The air conditioner unit is extremely hot.
Your home gets dusty.
The airflow is low and does not blow cold enough.