2007 Nissan Murano

Generally the first thing i would check is the water pump. As the bearing seal goes you lose pressure, and will get metal to metal contact. If you have plenty of coolant, this often means a circulation issue. Hope this helps.

I appologize. I read the entire issue, then address the wrong thing. This is actually a simpler fix. On A/C units, on occassion as the A/C clutch engages, there is occassionally not enough tension on the belt to move the pulley against the compressor pressure. The squeeling and smoking is the belt attempting to turn the pulley and failing. First, check the belt for excessive wear, second, tighten the belt by locating the tensioner, and third, belt dressing is a very cheap, yet useful tool for 3 bucks. Hope this helps.