Park you Nissan. Engage the parking brakes. Allow your Nissan engine to cool down.
Step 2: Open Hood
Open the hood of your Nissan. Look of the frame or under the hood for the serpentine belt routing diagram. It is often printed on a sticker found on the fan shroud.
Step 3: Locate serpentine belt tensioner
Locate the serpentine belt tensioner on your Nissan. You will need to move the tensioner away in order to release pressure from the belt. Take a few pictures with your phone of the old belt in case you need to look at the serpentine belt routing latter.
Step 4: Release Tensioner
Use a 3/8" ratchet to push the tensioner away(up) from the belt. To get to the tensioner you will either need to remove the passenger wheel or drive the car up on rams. Then you should be able to remove the plastic cover on the wheel well to access the tensioner.
Step 5: Remove belt
Remove the belt from the accessory pulleys by hand. The belt will need to come off several pulleys including, A/C pulley, alternator pulley, and crankshaft pulley.
Step 6: Install new belt
Install the new belt on your Nissan by making sure it is routed as per the belt routing diagram. The last step is to slide the belt under the tensioner. Before you do that make sure to check that the belt is properly seated on all the pulleys or you will have a hard time installing the belt.
Draw a diagram of the serpentine belt before you remove it or simply take a picture of the belt routing.
Visually check drive belts for damage or looseness before removal.
Be sure the ignition switch turned off and the key removed. If the engine starts unexpectedly it can cause fatal injuries.