Whenever I turn on the fan/AC there seems to be some whirring noises coming from the rightmost ones. It sounds like the fans are hitting something when they're spinning. Is there anything I can do about this?

 

Probably leaves stuck in the intake. Or pieces of leaves further downstream. Drove me insane until I tried this:

Clean what you can see and then get a honkin gas-powered leaf blower and run it through the vent backwards (i.e. blow in through the vent in the cabin) Close all the other vents. Do each one until the noise is gone....

-RMB

 

had the same noise in our 95 Altima SE, 01 Altima GLE and 97 Max SE. Pinpointed the problem to be from the fan blower itself located under the dash behind glove compartment. My 95 Altima SE never had the noise until I took the noise insolation cap off of it. It then sounded just like you described which can be heard in my other 2 cars. Also, neither of my other 2 cars came with this noise filter. I later found out Nissan dealers just started selling this par recently so check with them. I like Nissans but I don't like their cost cutting style.

 

OT but I agree with you on that, Nissan lately has seemed to pull the "GM' trick out of thier hat, mainly w/ interior materials