Same thing here, I'd say almost for sure it's the fan belt, or at least a belt. When they get a little looser (like after a new one is put on), they slip a lot more easily and make a squealing sound for about two or three seconds. The fan belt uses a ribbed design rather than a v-design for the belt which means that to get a strong grip it has to be tighter, otherwise it slips fairly easily when it gets hot or just looser.
The fan belt in ea-ed falcons is the worst fan belt for breaking or coming apart. The NRMA roadside assistance usually carries universal parts so that they can temporarily fix most cars, but the fan belt on the ea's is so bad, that the nrma actually carries the specialised belt as there is no universal belt in that size and design. HAHA! what a joke.
Hope that helps,