They're inside the plastic cover that protrudes forward from the passenger side firewall, just outboard of the passenger side valve cover.
You may have to pull some of the silver insulation off to see it.
You can sort of see in there at the evaporator by removing the heater blower motor (3 screws, passenger side inner fender, close to firewall), then using a flashlight and a mirror.
I removed my blower motor and flushed it off with a water hose.
It was caked with dirt, and grime! Here's a shot of what one guys looked like when he pulled his blower motor:
Evaporator Coil
The water will drain out of the bottom of the housing onto the ground.
Good Luck! /ubbthreads/images/graemlins/smokin.gif