Are you sure it only blows heat off the engine? When we discovered it, it blew cool air, not warm.
HDDP, try that button down there in CA on a warm day, after you turn off the car and see what the air feels like.
I figured that there may be some (ethnic group) that locked their family in their car and couldn't get them out! Then all the people in the car had to do to survive until their(ethnic group)father could get help, was push the "rest" button to give them some fresh air!!! [gee, you can't even tell (ethnic group) jokes anymore!]