In my 2001 volvo s80 are there any control modules in my rear view mirror

Yes, there are brains in there so you can't just swap auto-dimming with manual ones.
Like the previous answerer (hah) said, matching modules are key. If I remember right, you can synchronize them by locking/unlocking the car three times with the remote after they're swapped.

If you're lucky, your car doesn't have the auto-dimming leaking mirror. They get pricey.

Yes the S80/S60 and post 2001 V70 series cars have auto dimming mirrors which have a module designed to be programmed at a dealer when replaced. If you can read the car with Vida/Dice you can look in the Network settings to see the software version number. Only modules with a matching version number can be interchanged. If you care to browse Mattews Volvo Site you can find a repair method for this type of mirror by using the glass section from another mirror while retianiing the original controller board.