Why is my Honda Crv 2005 A/C is blowing warm air when I turned it on yesterday I heard a rumbling noise but the A/C was blowing cool air then it stopped working this morning.

Most all vehicles will initially blow warm air. The "rambling sound" would suggest an issue with fan blower or its associated electric motor. Hope this helps.-Michael Wayne Hendricks, 2:30pmCDT, May 4, 2018

I suppose that the noise came from under the hood, you should have stopped and investigate, it is not normal. Did you continue to hear other noises? Turn the a/c on and try to check if the compressor is working. Do you see/feel one of the lines (hose) from the compressor getting wet/cold. The a/c compressor may have developed a problem but continue to work for some time until it finally stopped.