T1ZZL3

This has not really been an issue until the other day. I noticed that the Drivers side fan was running insanely loud and the passenger side was not even on. Well I turned off everything the turned the truck back on, both fans kicked on, then the passenger side fan shut off the drivers side fan sped up and got loud. I know it will happen with the A/C on, but it runs like that from ignition until I turn my truck off, it never slows down and the passenger side does not turn back on. It is almost like the driver side is compensating for the other fan turning off. I hope I am just being ignorant, but if there is something wrong I would like to know so I don't waste money at the dealer to tell me there is nothing wrong. Thanks every one for any help you can throw my way.