help explaining vacume for air conditioner
 

got the info that my air conditioner problem is the result of a leak in my vacume or bad vacume. I found the pump and when I put my finger on the outlet hole it would vibrate and start working and the air would start up again inside the cab. Is this vacume pump running all of the time the air is on or does it store vacume in a pot that I need to identify and check for leaks in the pot or lines running to it. On my last trip of 7 hours the air would work fine for a couple of hours, the go off, then run and not run for about 1/2 hour intervals. Thanks for any help.