I have a 2006 Merc 225 Pro XS started up and run no problem. After a few hours fishing started had a whistle sound coming under the cowling on at idle. Noticed my electronics blinked at start up (battery full charge). Took off the cowling when off the water and the tensioner pulley going bad (replaced already)possibly the alternator going bad (don't know yet) and hope not the compressor. Going to replace the belt also can I use an Autozone belt 310K4/ Dayco K040310 which cross references to the Quick Silver 852385A2? Also how can I trouble shoot the compressor prior to bringing it in?