A/Cwont always blow cold on 2003 Toyota Matrix

A/c wil blow cold and then will stop blowing cold air and will blow warmer air for awhile and then it will just start blowing out cold again. This just started and it happens while driving on the highway as well as in town.

Asked by for the 2003 Toyota Matrix
AC evaporator temperature sensor, have it check. My car did the same thing and I had sensor replaced, work find now.