theres one on the coolant reservoir. I had a how to from here when I drained mine.....Dang pics are gone but theres a walk throughhttp://matrixowners.com/?showtopic=33044&st=20
I'm not aware that there is an air bleeder on the cooling system (wish there was) but I do know that it is somewhat difficult to get the system to "burp". Done it twice and had difficulties both times. Do a search to find the procedure I used to finally get the system burped.