Fuse 8 15A (LG/Y wire on switch & fuse panel)
Other things that run on that circuit include the illuminated entry, dome lamp, clock, power antenna, instrument panel illumination.
If those other items aren't out also (which they probably aren't or you would have noticed), you probably have a bad switch. Check first for always-on 12v on the (LG/Y) wire going into the back of the switch, and make sure the black (ground) wire on the switch actually gets ground. It is not likely that all four motors in the mirrors are burned out, but some dummy could have unplugged both mirrors inside the door while removing them and never re-connected them - its worth checking that too.