[Shop-talk] Weird car alarm behavior

[Bob Spidell]

I've been trying to repair an oil pan for my Austin-Healey that I 
cracked on a steep driveway lip by welding the crack (it's coming 
along).  I'd pulled my 2008 Mustang out of the garage onto the driveway, 
and was cleaning the pan with dish soap and water.  When I blew 
compressed air on the pan to dry it, it set the alarm off in the 
Mustang!  Just to be sure, I tried it twice, and both times the car 
alarm fired when I blew air into the pan.  Apparently, some frequencies 
of sound or some other phenomenon besides earthquakes can set these 
things off; any experts know what causes this?

Bob