Turn that heat off at night too! Corn snakes do just fine in the 70's. Do NOT let it get over the upper 80's- 92 is way too hot for a corn snake. (I keep corn snakes- many, & for decades.)
You could put a small ice pack, a cold gel packs or a bottle of very cold water next to, in, or on top of the tank. Keep in mind that the colder it is, the more condensation these options will produce-it's best not to put ice in the tank but if you do be aware it will also cause dripping- fortunately your corn snake will probably enjoy that. Less messy would be cold (from the frig.) re-usable gel packs- & you could put them on the screen top* (*I'm assuming?) because remember that cold air sinks, & warm air rises.(same goes for containers of very cold water, but be careful that your screen top is sturdy enough for the weight of whatever you're using) Use whatever you have & just see how that goes- I'm sure your snake will appreciate some relief. A few ice cubes in the water bowl will help too- but will quickly melt & not last all day (like if you're away at school or work).
Fans do NOT help a snake to cool down because snakes don't perspire- fans only help cool the air a little when the air is going thru water, as in a "swamp cooler" (aka "evaporative cooler"), or we humans, because we perspire.