Changing air filter for the A.C?

When changing the air filter, is the air filter located outside where the fan is, or inside where the other part of the AC is. I can%26#039;t find where to put in the new air filter|||same as the furnace filter, they are one in the same filter.is no filter outside. specify for what?|||What vehilce?/On a Ford product its usually in the compartment up front soon as you raise the hood/|||if it%26#039;s a house a/c unit it%26#039;s by the fan. if on car it%26#039;s by the top of motor in a casing.