2003 Infiniti Q45 REPLACING SERPENTINE BELT

You have two belts and two tensioners on your engine. They're all located on the front of your engine.

One belt operates the alternator, A/C compressor and water pump, the second belt operates the power steering pump.

To remove the belts, you must insert a breaker bar into the pulley on each tensioner (the belt for the power steering pump is first) and push/pull the tensioner until you remove the tension on that belt. Then the belt slides right off.

If you are tackling this job yourself, I suggest you purchase a service manual for your vehicle. AutoZone sells them for 25 bucks (Hanes or Chiltons). They'll provide you with detailed illustrations and procedures as well as come in handy on your next project. (They'll also give you a list of tools you'll need for each procedure)