Hello, first time xterra and i love it. altho it needs some love. the heat isnt coming on and if it does it is very brief, was thinking maybe heater core is clogged?? any one had this problem before? also have a wiper not wiping. right side and i dont hear any loose linkage so not sure. wanted to se if anyone had any input before i take the cowl off, never done that before. thanks for any and all help.