2011 M37

Hi everyone. I live in Tucson AZ and my outside temps are reaching 108F in the afternoon so you figure my a/c is at almost full blast plus both of my fans would be running at high. The issue that I'm having is that when I stop at a light, after 5-10 seconds, it feels like one of the fans starts vibrating enough that I could feel it on my brake pedal. Now I'm not ruling out that it could be the compressor also but I'm guessing the fan(s). Of course everything goes back to normal if I turn off the a/c. I just discovered this issue today so I have not really checked it out. Any input would really be appreciated.Thx ahead.