I did a little bit of research on Perdido a little while back, though had to cancel the trip
The last stage of the ascent, from the pass between Cilindo and Perdido to the summit can be icy, even in summer; I believe it is reasonably sheltered and north-ish facing. Very patchy though, so I'd be surprised if ice gear was essential. The other two peaks certainly don't have icy approaches in mid summer.
I can't find any of the photos I tracked down on my first search, but a little hunting around on the internet might turn up something useful.
If you look at this OM thread you'll see a mention of an August trip where crampons and axe were unnecessary.