It will search the other bands such as 225-400, but you have to enable them.
To do this, start a service search on the aircraft band like you've been doing.
While searching, press the "MENU" button and then scroll down, as you scroll down you'll notice the other freq ranges, if the range has a check mark next to it, it's enabled. If the range such as 225-400 has a square box next to it, you have to press the "SEL" button to put a check next to it.
Once you've selected the ranges you want to search, press the "LEFT ARROW" key and then the radio will ask if you want to save the change, press the "SEL" and the radio should go right back to the search.